Ok this one gets a little bit complicated but bare with me :D

A client brought her computer in to be fixed about a week ago, she says she tried charging a new phone she bought from china and immediately after her usb keyboard and mouse stopped working (typical).

I had a quick look at it but because I did not have time, I did a simple system restore and it seemed as if the issue was fixed. I promptly sent it back to her but a few days back she called saying that the issue has returned. Turns out the computer was riddled with some virus that also corrupted her XP install so I had to format the whole thing(yes I tried repairing). I hoped that the format would fix the keyboard and mouse issue but the whole thing has escalated and the computer will throw the "USB Device not recognized" error when I plug anything into the many usb ports it has. I have installed all the drivers (including the chip set drivers) for the pc and even tried the unplugging from the power for a while trick, still no luck. I am sure it is not a hardware issue, but may be wrong.

This is way over my head. Can anyone help?

Computer: HP Compaq DC7100, Intel Pentium 4, 512mb RAM

OS: Windows XP Professional SP2