Well, here is what I would do:

1. Back everything up that you can (emails, address book, write down all your settings).
2. Test out your backup to make sure it works (on a different computer?)
3. Uninstall OE from original computer
4. Reinstall OE
5. Put everything back on
6. If OE still doesn't work, find another email program or reinstall windows

This could take you anywhere from 15 minutes to an hour.

-Biscuits