Latitude D620. Has been working fine with a USB connected Promethean ActivBoard at a school.
All of a sudden the Board starts having issues. Stops reponding to NB, won't see the pens, etc.
After troubleshooting board, we try an older Toshiba NB. Same software, drivers, cables etc. Board works fine.
Brought in another D620 to that room, (setup for board at another location) it also works fine. Swap in the original D620 and instantly the Board stops reponding. Immediate. There is a little symbol in corner of board, that when this NB is plugged in, blinks red a couple times as board turns off.
Tried re-imaging the original D620 and fresh loaded software and latest drivers for Board (that worked perfectly for months) and problem instantly re-appears when board is plugged in. Assume USB hw problem.
Your troubleshooting process seems sound and your conclusion that the USB port is failing is also sound. You can either add a PC card with USB ports to replace the failing ports on the motherboard or you can replace the motherboard. If the system is still under warranty, contact the Dell Techies to validate your troubleshooting and to have the mobo replaced. If the system is not under warranty, you can consider replacing it yourself or simply installing an expansion card as noted above.
Dell sent tech out and replaced motherboard.
Worked great for one day.
Now has same symptoms and back to using old Toshiba NB (which works fine!).
I'm at a loss.