Uninstalling SP2 is not the answer. SP2 fixes hundreds of XP bugs and improves PC security, especially for the Home user and non-technical user. To resolve your issue try the following in the order specified.
1. Update Windows from the Windows Update site. This will also update Internet Explorer and will ensure that you are using all the latest components.
2. Clean up your hard drive.
3. Run chkdsk c:/r to fix any file problems.
4. If you are using a 3rd-party Firewall then you must choose between the Windows Firewall and the 3rd-party Firewall. You should not run both on the same system at the same time.
5. Update your AV software program files. Some AV software will cause problems if not updated to work with SP2.