So my USB flash devices aren't working

My USB camera, printer, keyboard, mouse work fine.

When try to sync my iphone, however, it tells me after a few minutes that "the device has timed out".

Similarly, with my USB flash drive, i can copy/paste files for a couple minutes, until the computer can no longer detect the USB drive, and tells me that the "parameter is incorrect" for the file i'm copying.

I've tried
-updating my drivers
-uninstalling my USB drivers, then allowing them to reinstall
-ensuring that the will not be turned off to save power

For some reason, i can't connect to windows update.
I have about 6 gigs of media that i'd like to save on this computer so reformat is out of the question

My computer is running
XP Pro SP2
intel 915g motherboard
2 gigs of ram

Any help would be much appreciated.

Thanks!