This is one mystery that I am totally unable to solve.

I use a Thompson Speedtouch 121g USB wireless adapter on my Compac Evo N610c notebook with Windows XP Sp2. Never had any problem until 2 days ago when I turned it on, plugged in the adapter and promptly got a BSOD. This happened everytime I tried to plug it in and if I left it in during reboot it never got past the splash screen before going blue. Even though I've disabled the automatic restart the BSOD still only lasts 2 seconds and then disappears. Although there is no error description listed the technical information section indicates:
STOP: 0x000000007f which I believe is: UNEXPECTED_KERNEL_MODE_TRAP

The Event ID is either 1003, which covers a multitude of sins, or ID7000 which comes from the System Control Manager and states that the Prismsvc service failed to start as acess was denied.

I have made no configuration or hardware changes and have not overclocked this system; further, I know that the USB ports all work because I use other devices on them without any problem. The adapter itself works fine on another labtop so I'm really at a loss to know where to look. I also tried uninstalling and reinstalling the speedtouch driver with the latest driver update.
Any help would be appreciated.

can you post at least the first paramter of the stop error
**STOP 0x0000007F (0x000000XX, 0x00000000, 0x00000000, 0x00000000)

0x00000008. I had like 2 seconds to read it but that's what I got.

according to ms knowledge base this is a "double fault"

Double fault
A double fault occurs when an exception occurs while trying to call the handler for a prior exception. Normally, the two exceptions can be handled serially, however there are several exceptions that cannot be handled serially and in this situation the processor signals a double fault. The two primary causes for this are hardware and kernel stack overflows. Hardware problems are usually related to CPU, RAM, or bus. Kernel stack overflows are almost always caused by faulty kernel-mode drivers.

RESOLUTION
To resolve this issue, use the appropriate method:
• If either software or hardware can cause a particular trap, a debug is required to determine which is the cause. If you suspect a hardware problem, try the following hardware troubleshooting steps:
1. Test the RAM in the computer by running the diagnostic software that is provided by the computer manufacturer. Replace any RAM that is reported as bad. Also, make sure that all the RAM in the computer is the same speed.
2. Try removing or swapping out controllers, cards, or other peripherals.
3. Try a different motherboard on the computer.
• If you are over clocking the speed of your processor, set it back to the speed at which it is designed to run.
• Check with the hardware vendor for any updated hardware drivers or BIOS updates, or both.

personally I had a similar isue with a dell latitude c400 and a pcmcia wlan card. the issue was the video driver which did not work when the card was plugged in or vice versa... a newer driver fixed it.

Thanks for your reply. Coincidentally,while waiting for your answer I found the same ms link you quoted.
I sure hope it's not the mbo.

ok, good luck and try the drivers. I think thats the best to start with