click here download and use. Then click here download and use. Especially use the history feature, then use clean registry.
Type sfc /scannow (note space between sfc and /)into start-run and click OK. This will check your files..you may need your XP disk.
Type msconfig into start-run and select 'startup'. Untick everything that you do not need (real player, office etc.) reboot and see if all this made a difference.