usb 2.0 thumb drive ceases to be recognized.

Hi,

I have a user that has a usb 2.0 thumb drive.  he was in the habit of yanking it out before "stopping" it.  this morning something went amiss.  
the machine is a compaq d530 SFF  win 2k sp4 with all the latest patches,  no viruses, or spyware etc...

this machine has 6 usb ports 4 in the back and 2 in the front.   the thumbdrive will only work in one port in the whole machine. (the rightmost one on the front, for whatever that's worth.)

I know his thumb drive is good because it works in my machine, and my thumbdrive (a different model) works in all ports on his machine.

here is a list of things I've done.  
removed all usb hubs and controllers in safe mode. and reinstalled.  
shutdown and started from a cold boot. (sometimes this helps..)
went through the registry looking for Lexar and JumpDrive and removed the entries. (some I had to change permissions on to remove.)
stopped the removable storage manager, renamed all the file in the ntmsData (sp?) folder in winnt/system32 and rebooted.

updated the intel chipset driver bundle to the latest rev from compaq's site.

the only clues that  I have is that after this happened , the event viewer is showing

event id 256 from the plugplaymanager   (at boot up) (everything I've read says to disregard this message....)
and event id 17 from the removable storage manager.  when I remove his device from the only port that's working for him.

basically what is going on is that it is not seeing this particular device at all.  and I'm not sure how to reset the usb so that it will see this device again.  I've done a lot of googleing on it and haven't really come up with anything.  I know the hardware itself is good because of the testing that I"ve done...  

Thanks for  the help.
Tanelorn