DAQ-USB/GPIB-USB "forgotten" by Windows

[theoneandonlyjim]

I've been working on a bug for sometime now.

On two separate Windows systems (one XP and another Vista), I've run into a situation where I temporarily lose connection to a tool connected by USB - just long enough to throw an error in the code and stop the program. I have been thus far unable to figure out a set of conditions which induces this failure, which appears at irregular intervals: 700+ hours, 400+ hours, 48 hours after test start. This has now happened with a two different GPIB-USB and SCXI-1600 connected by USB.

I've been told (and observed) two things: that occasionally Windows will selectively suspend USB inputs to conserve power or that the USB inputs will compete for resources. I have observed one tool to be unresponsive to *IDN queries until restart and another to be perfectly healthy when investigated.

As such, I've tried a couple of things:

-Edited the registry to disable selective suspend - the failure's happened once since then, but there are more "USB" prefixed keys in the registry - should I disable them all?

-Added a separate USB card so that my tools aren't sharing resources with the mouse and keyboard - the failure has happened multiple times since then

-Disabled all hibernation, sleep, and power off options

A couple more were suggested by NI:

-Reset Resource VI - I have yet to get the example VI in LV10 to work.

-Changing to Windows 7

-Making connections with a GPIB-GPIB - not only is this out of budget, but it doesn't help for the SCXI

I've thought of another:

-Cutting the USB cable open, clipping the +5 VDC and putting each side on two halves of an SPDT switch connected by RS232 - effectively unplugging/plugging the cable as a manual reset.

Since this is such an irregular error (and sometimes leads to thermal runaway), I'd like to apply as many backup solutions as I can before I commit more samples. Has anyone else had this error, and if so, did you try anything different?