When you say it does not boot, how far does it get? Does it appear to start loading Windows or does it never get out of the bios?
 
I ask because there have been some machines with a bios that will not load the OS when a USB device is connected that has a descriptor that the bios doesn't like. There are some aspects of your description that point to the Tascam h/w or the USB cable being flaky.

This works with windows drivers. So, this is clearly an asio driver issue.
 
the tascam dude wants me to call. 
 
I will when i have time. But, leaning toward selling it.
 
My nearly ten year old emu with five year old drivers works mostly fine.
 
Disapointing.

Update:
Called the tascam support dude: no ideas at all, except something is wrong with the hardware.
 
So, for grins I tried changing the driver to WDM/KS. This resulted in the track playing, BUT only noise.
So, I changed it back to ASIO:  AND IT WORKED!!!!!!!!!!!!!!!!
So much for the hardware being bad.
I restarted, and tried again, but NOOOOOOOO!!
I changed to WDM/KS and back again. This time it takes two toggles, and it works.
I change the windows audio settings, and it does not work.
I change the windows audio settings to defaults, restarts the computer, toggle to WDM/KS and back to ASIO and it works.
 
This is just stupid.
 

I think the Tascam dude has it right, its a hardware problem - i.e. a defective unit.  Its possible its got corrupt firmware in it which is causing intermittent operation.  If they are offering to replace it, I'd take him up on the offer.  You don't really have anything to lose.

I can repeatedly get the unit to work by toggling the driver.
 
But, it requires COMPLETE and EXCLUSIVE control for Sonar to work. Which means i cannot use any other audio programs while sonar is open.
 
This is a software/driver issue.

If this is a hardware issue then tascam has manufactured hundreds of defective units.  I am not inclined to believe this.
 
There are messages in dozens of forums, including CW's, that identify problems. 
(New USB cards to fix noise,...)
 
Too many have had problems, and many have abandoned these units.
 
Something is wrong with the drivers.
 
Is it AMD based boards? particular chipsets? Video cards?
 
There has to be a commonality about all the problems.
 
This has been a very disappointing experience.
 
 
 
 
 
 
 
 

I believe there are problems in the drivers for sure.  In my specific case, several DAWs (SONAR, Reaper, S1-3, Tracktion, MC8) all have the same problem.  The symptom is latency when switching presets in certain VIs and FX.  This include Sample Tank, AmpliTube, Waves GTR and others.  I can clear it up by going into prefs and selecting a different interface, then reselecting the 16x08.  Everything works great until I select another preset/model. in the plugs.
 
This does NOT happen using other interfaces, including Zoom R24, UMC404HD, GT-001, FA06 - none of which have this problem.
 
I'll soon be getting a new DAW.  If the problem with the 16x08 persists then it will either get thrown in the weeds or be relegated to stand-alone preamp and software-controlled mixer duty.  I was planning a new DAW anyway ...
 
I otherwise love the 16x08.  It's too bad it's sucking away my will to live
 
I still think there is a hardware problem if it interferes with your machine's ability to boot.

jm24
I can repeatedly get the unit to work by toggling the driver.
 
But, it requires COMPLETE and EXCLUSIVE control for Sonar to work. Which means i cannot use any other audio programs while sonar is open.
 
This is a software/driver issue.

Actually, ASIO drivers do not share well with other programs on any interface.  Do you have "Share Drivers with Other Programs" checked in preferences?
 
 

Have you tried replacing your standard ASIO driver with ASIO4all??

I had a similar problem in the aughts where the RealTek would take control every time I started the computer.
My solution: I removed the RealTek HD audio program from the computer.
That computer is still going strong some 10 years later with my Focusrite Saffire playing from all sources.