819017 - Long Delay Before Files Appear in My Computer in Windows XP
Also see how it goes if you switch off anti virus software for a few moments.
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.
Spybot
Ad-aware
Will check your computer for spyware and adware.
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 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
Some general things to try.
See if System Restore will get you back to a restore point before your problem with Explorer.
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. You will lose all your windows updates but your files will be untouched.
How to Perform an In-Place Upgrade (Reinstallation) of Windows XP (Q315341)