1) Try a system restore to as far back as possible.
start, accessories, System Tools and click system restore. Follow directions.
2) Shut down completely, unplug from the wall, wait 30 seconds and reboot.
3) C:\>sfc /?
Microsoft(R) Windows XP Windows File Checker Version 5.1
Scans all protected system files and replaces incorrect versions with correct Microsoft versions.
SFC [/SCANNOW] [/SCANONCE] [/SCANBOOT] [/REVERT] [/PURGECACHE] [/CACHESIZE=x]
/SCANNOW Scans all protected system files immediately.
/SCANONCE Scans all protected system files once at the next boot.
/SCANBOOT Scans all protected system files at every boot.
/REVERT Return scan to default setting.
/PURGECACHE Purges the file cache.
/CACHESIZE=x Sets the file cache size.
C:\>sfc /?
4)" To reset your computer back to the factory setting you will need to use the CDs that came with it. Insert the first CD and it will guide you through the process. If you do not have this CD then visit the Dell website. Enter your service tag and go to the downloads for your system.
Part way through you will be prompted to insert the Microsoft Windows CD that also came with your system.
Ensure that you also have your Microsoft Windows serial number."
5) "If your computer shows a blue bar at the top of the screen and says www.dell.com you can try ctrl+f11 which will start the system restore sequence......"