XP dosn’t see USB

My Pentium III 366mhz, 512mb ram, 30gb hdd, with I recently loaded WinXp, all was fine for the MOST part, however recently system does not recoinize any of my devices connected via USB ports, I have a USB visioneer 4400 scanner that was working fine, thank you very much, and now not only does the system not reconize my scanner, but my ms usb track ball dosn’t work either or my usb connected pc flash card reader.

I disconnected the track ball and card reader in an attempt to see if they were’draging down’ the signal, but that didn’t work.

Should I try to reload winXp pro?