To get further information about the error look in your Event viewer.
Look in the System or Application folder. You can get to the Event Viewer via right click My Computer icon and select Manage.
Any errors logged in the Event Viewer can be expanded by double clicking on the error line.
Take any event error I.D. number and search for it on these sites.
If the error occurred after installing a device driver or application, try using Safe Mode and removing the driver or program.
To check your RAM.
To check your Hard Drive.
The drive manufacturer will have free diagnostic software to check your drive for problems.
To check your drivers.
HOW TO: Verify Unsigned Device Drivers in Windows XP
To check conflicting software.
310353 - How to Perform a Clean Boot in Windows XP
316434 - HOW TO: Perform Advanced Clean-Boot Troubleshooting in Windows XP
310560 - How to Troubleshoot By Using the Msconfig Utility in Windows XP
Removing adware & spyware
faq608-4650
Will check your computer for spyware and adware.
See if you have any services that are flagging as "Starting" but not actually running.
Some general things to try.
See if System Restore will get you back to a restore point before your problem with Windows.
Try Safe Mode (Do you have this problem in Safe Mode?).
Try running ChkDsk to check your drive for errors. Right click your Drive icon/ Properties/ Tools/ Error Checking.
Run the System File Checker program from the Run Box by typing.....Sfc /Scannow in it and have your XP CD handy.
If they don't work you could try repairing windows itself by running it over itself using the Recovery CD.
These are some examples of text problems, I can't see that they apply but they do show what can happen and why.
Problems with Outlook Express
thread779-1110771
Delayed Response When Editing Internet Explorer Forms and Outlook Express May Take a Long Time to Start
NOTEBOOK TYPES BY ITSELF!!??
thread779-564000