What is the picture like from Safe Mode? Try Safe Mode and at the Welcome Screen (if you use it) press Ctrl+Alt+Del twice to bring up the classic logon box and then logon as a limited user.
In Normal Mode as a limited user, does Ctrl+Alt+Del (once) bring up Task Manager where you can use File/ New Task Run to launch Explorer?
If any of the above work try a process of elimination to isolate the problem.
Removing adware & spyware
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Microsoft (GIANT Antispyware) Beta available
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There is also the consideration of a corrupted Profile?
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Some general things to try.
See if System Restore will get you back to a restore point before your problem with Explorer.
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.
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If they don't work you could try repairing windows by running it over itself. You will lose all your windows updates but your files will be untouched.
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