Urgent help please - lost USB connection

[Guest Bingo Accent]

I bought my daughter a bluetooth dongle for Christmas, so that she could transfer pictures from PC to her phone.

Whilst I never managed to successfully set this up, in trying to figure it out I did manage to get my C500 to ActiveSynch via bluetooth, having found a step-by-step guide on the web.

My problem is that I have now lost the ability to link via USB - I'd rather just plug the phone in, than mess about pressing buttons, and in any case, I use the USB cable to power up the phone.

Whenever I plug in the USB cable, the PC does not recognise it and I get an error message. I've tried it in other USB ports, and tried swapping a webcam in to the phone's port, and it's definitely the device/cable that's the problem, not the port. I've reinstalled ActiveSynch, thinking that this would include USB drivers, but that hasn't worked. I've even swapped to a different USB/mini-USB cable, but that hasn't worked.

Any suggestions, before my phone battery goes dead??