dlion16
Focusrite tech support rocks! Chatted with nick

I know right. I said the same thing. I believe it was Brandon who helped me.
A lot can be said for good support. it brings buyers back. Glad its all sorted Dlion

I've had several dealings with Focusrite support when I had a Saffire Pro 40.  The responses were fast and either solved the problem or offered helpful suggestions. 
 
When I wanted a backup recording interface unit, I went with a Focusrite (6i6 2nd gen).

Do you know the driver version he sent you? was it 4.26? I tried that one with no luck just curious.
 
 

About that USB 2 versus 3 tip, my new 18i20 2nd gen. was plugged into USB 3.  I plugged it into USB 2 on top of my case, as there is no USB 2 port on the back of the PC, only 3.  Even after rebooting it didn't work at all!  I couldn't get it to lock the digital link. 
 
When I went back to the USB 3 port, all was fine.  Surprise...
 
 

Thanks, chuck. Emwhy, it is 4.26. Much better than the  previous. I'll do more testing tomorrow. 

I spoke too soon, yet… 
The beta driver helped, glitches were fewer, but still there.
Another round of deep chat with focusrite techs, after making the suggested bios changes, again much improved.
I did some research, others had issues with lan adapters. I had disabled in devman, now I also disabled in bios. Again, much improved. 
Then I did the unthinkable, after once again seeing ms usb 1.0 and 2.0 driver issues in latencymon, I switched from a usb 2 port to usb 3. 
Bingo, haven't had a glitch in 3 days. Those old ms usb drivers from 2006, the latest version available, could not be updated, all my usb 3 drivers were. Latest asus usb 3 drivers seem to have no problem with a usb 2 device… 

dlion16
yes, chuck, usb2 port. before was m-audio firewire 1814. should i also uninstall the 1394 driver? how do i check the firmware version?
 
emwhy, how do i check to see if the usb port has its own root hub?
 
thanks.

http://www.uwe-sieber.de/..reeview_e.html#download

Thanks, soundwise, but I think not using a usb 2 port made the difference, contrary to conventional wisdom. The asus usb 3 driver and ports are friendly to usb 2 devices, at least this one. And turning the wired lan port off in bios helped too… 

I used mine on a pcie card with 2 USB 3.0 ports. Glitch free and I was able to notice a dip in overall CPU usage plus it was ultra stable with smaller buffer settings. Gotta get these things on their own ports and hubs and not have them sharing USB bandwith.

Disabling LAN in BIOS seems very disruptive if you ever want to use that computer on line. Also seems curious that you had so many interim steps that helped but did not quite fix the problem. I find that unless an issue is occurring at a regular interval or under a specific set of circumstances it is difficult to know if an adjustment really contributes to a fix or not. In other words, perceived improvements could have due to the randomness of the glitch. Since plugging into usb3 has (oddly enough) completely fixed the problem it seems possible or even likely that it would have fixed the problem completely even if it was the first thing you tried. You might consider reversing those changes (esp the the  BIOS disabled LAN) and see if if glitches recur. Of course if you dont need the LAN it doesnt matter, but for many that would be a big inconvenience to go into BIOS every tkme you needed your network.