start-run-type SFC /SCANNOW-enter. You will need the xp cd.
If that doesnt work you may need this.
How to do a system repair.--Boot from the xp cd and go past the recovery console to the install menu. Select repair the existing installation. You won't lose any data except the xp updates. Unless you have a slipstream sp1 cd you will have to d/l sp1 and all subsequent updates. You MUST have at least SP1 installed and the updates for security reasons. Be sure the firewall and A/V is active before going online as you will be susceptible to sasser and msblaster. If you don't want SP2 go to autopatcher.com and d/l SP1 and subsequent updates.
i followed the official windows site to this problem, they said enable plug and play threw the instructions they gave. i followed the instructions and it seems that plug and play is already on and started. i dont know what else to do