Anderton
I just sent off the thread URL for comment. I'm still confused as to why I can play as much audio as I want, including SONAR running ASIO and Windows running multiple sound sources, and you can't. I don't know what difference in our systems would account for that...maybe TASCAM will be able to reproduce your issue and report on a solution.

Anderton , where did you send it ? is it possible to give me their email ? I am just wondering , it can't be Tascam to have such bad support. 

I didn't go through support, I sent it to one of the engineers. He might still be trying to reproduce it.

Anderton
I didn't go through support, I sent it to one of the engineers. He might still be trying to reproduce it.

Thanks for letting me know Anderton. I am not sure if reproducing will work . my opinion is to make a driver more stable in a general form of meaning , for example , a driver that could work in any circumstance , without any need to disable any other onboard drivers on the system (like your situation) to get them working in a decent way. That might do the tascam drivers more powerful to prevent any future bugs. 

At Cakewalk's request, TASCAM has been looking into the reported behavior.   We have identified a problem and are working on a solution.
 
Tom (TASCAM)
 

Cool! Thanks, Tom!!

TomDuffy
At Cakewalk's request, TASCAM has been looking into the reported behavior.   We have identified a problem and are working on a solution.
 
Tom (TASCAM)
 

Thank you for letting us know Tom. It's a relief to know. I am looking forward to any updates. 

Recap for TASCAM support - for customers in North America, please use the page here: 
http://www.tascam.com/contact/support
 
This _will_ generate an auto-response email with a unique Reference number in it.   If you say "I never got a reply", we need you to supply that Reference number so we can look up the conversation.
There is also the phone support line for North American customers. 323-726-0303 ext. 617 (M-F, 8am-5pm Pacific).    Our guys are regular users of our gear, so they can usually spot the hiccups people run into.
 
For customers in the UK, there is this page:
http://www.tascam.eu/en/support-uk.html
 
For the rest of Europe:
http://www.tascam.eu/en/supp_interfaces.html 
 
These two are not as automated. The TEAC EU staff rarely drop things, but they may need more time to research answers.   Things that don't seem right normally reach me through these channels, but we do not read all the forums directly, so we need you to tell us directly what problems you are seeing.   Of course linking in a support request to a forum discussion is fine for providing background.
 
For elsewhere in the world, find the correct email contact by starting here:
http://www.teac-global.com
 
If it comes down to "we're not sure what's going on", we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer.  Accurate information always helps.
 
Tom.
 

TomDuffy
Recap for TASCAM support - for customers in North America, please use the page here: 
http://www.tascam.com/contact/support
 
This _will_ generate an auto-response email with a unique Reference number in it.   If you say "I never got a reply", we need you to supply that Reference number so we can look up the conversation.
There is also the phone support line for North American customers. 323-726-0303 ext. 617 (M-F, 8am-5pm Pacific).    Our guys are regular users of our gear, so they can usually spot the hiccups people run into.
 
For customers in the UK, there is this page:
http://www.tascam.eu/en/support-uk.html
 
For the rest of Europe:
http://www.tascam.eu/en/supp_interfaces.html 
 
These two are not as automated. The TEAC EU staff rarely drop things, but they may need more time to research answers.   Things that don't seem right normally reach me through these channels, but we do not read all the forums directly, so we need you to tell us directly what problems you are seeing.   Of course linking in a support request to a forum discussion is fine for providing background.
 
For elsewhere in the world, find the correct email contact by starting here:
http://www.teac-global.com
 
If it comes down to "we're not sure what's going on", we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer.  Accurate information always helps.
 
Tom.
 

Thank you Tom for all details. 
I already did this. My reference is > 
Reference: ECIFKJ72 
When I tried to send more information to the same email : Array@aws.teac.com
the email bounced back to me writing that "can't deliver cause time out" ! 
Now If I cant send emails to Tascam how possible I could help them to fix the drivers ? 
Also I just found a new problem . that after 8-10 hours of my PC computer running continuously , the audio is disabled by it self. 
It seems that there is a power in problem with the rack interface.  Then I have to turn off and turn on the rack to get sound back , but it will only work for 10 mins. I have to shut down the PC and then turn it on to get back to windows for a completely fresh reboot and to get audio back for another 8 hours session. 
 
 

Etostone

TomDuffy
For elsewhere in the world, find the correct email contact by starting here:
http://www.teac-global.com
 
If it comes down to "we're not sure what's going on", we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer.  Accurate information always helps.
 
Tom.
 

I already did this. My reference is > 
Reference: ECIFKJ72
 
When I tried to send more information to the same email : Array@aws.teac.com
the email bounced back to me writing that "can't deliver cause time out" !
Now If I cant send emails to Tascam how possible I could help them to fix the drivers ? 

 
I just sent a test email to verify that address and did not have any problems. It was sent and delivered. [EDIT: A couple hours later, I received an "email delayed" reply. So it does look like there's an issue. I will alert TASCAM.]
 

Also I just found a new problem . that after 8-10 hours of my PC computer running continuously , the audio is disabled by it self. 
It seems that there is a power in problem with the rack interface.  Then I have to turn off and turn on the rack to get sound back , but it will only work for 10 mins. I have to shut down the PC and then turn it on to get back to windows for a completely fresh reboot and to get audio back for another 8 hours session. 

 
I don't know why you have these issues. I run my US-4x4 for hours without problems. But if I'm running for hours that means I'm just using SONAR, not switching back and forth among other programs. I assume you have all your USB ports set so they don't suspend power.
 
As Tom says, "we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer." Only then can they see a pattern develop that relates to the interface as opposed to its interaction with a particular system.

Anderton

Etostone

TomDuffy
For elsewhere in the world, find the correct email contact by starting here:
http://www.teac-global.com
 
If it comes down to "we're not sure what's going on", we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer.  Accurate information always helps.
 
Tom.
 

I already did this. My reference is > 
Reference: ECIFKJ72
 
When I tried to send more information to the same email : Array@aws.teac.com
the email bounced back to me writing that "can't deliver cause time out" !
Now If I cant send emails to Tascam how possible I could help them to fix the drivers ? 

 
I just sent a test email to verify that address and did not have any problems. It was sent and delivered. [EDIT: A couple hours later, I received an "email delayed" reply. So it does look like there's an issue. I will alert TASCAM.]
 

Also I just found a new problem . that after 8-10 hours of my PC computer running continuously , the audio is disabled by it self. 
It seems that there is a power in problem with the rack interface.  Then I have to turn off and turn on the rack to get sound back , but it will only work for 10 mins. I have to shut down the PC and then turn it on to get back to windows for a completely fresh reboot and to get audio back for another 8 hours session. 

 
I don't know why you have these issues. I run my US-4x4 for hours without problems. But if I'm running for hours that means I'm just using SONAR, not switching back and forth among other programs. I assume you have all your USB ports set so they don't suspend power.
 
As Tom says, "we have to wait to see if a similar thing occurs for other users before we can see how to divide and conquer." Only then can they see a pattern develop that relates to the interface as opposed to its interaction with a particular system.

I am glad to see another person has similar problem with Tascam email. Strange isn't it ? Why do I have to be the first to find their weak spots ? They need to hire me as their bug reporter both in software and hardware and email services. 
From my experience I believe that the firmware needs another update. Turning off and on the rack device is very often happening here. I don't have any USB power suspend option enabled. 
 
I feel that USB racks are not reliable for pro sound productions. I am thinking to sell the Tascam USB 4x4 rack and move to PCI -e soundcard interface so I can work properly . I still use my older PC with the M-AUDIO 1010lt so nice audio workflow. 
 
Still it's a pity that hardware can't keep up 2 date to the latest updates of Windows , computer system and other software. 
Thank you Anderton for your kind support.