It's probably a totally different problem, but i had trouble with my usb ports, they just wouldnt recognise anything, i found out that my drivers had mysteriously dissapeared, and there were none on my recovery disk, so i had to search all over the internet for the proper drivers, found them in some distance corner of webspace. The still play up a bit, but work most of the time now.
If you have Windows XP, have you upgraded to service pack 3? That might be a cause or solution, i don't know. Have you made sure your drivers are up to date?
Also try reinstalling or updating windows media player, i know that causes some problems when trying to use MP3 players, not sure about phones though.
