The issue: Outlook Express is not showing the content of any message, you just see a blank / white window.
Click on Start > RUN > type “%temp%”, without the quotes, just %temp%.
You should see a bunch of files and folders.
You have to delete them all. Those are Windows temporary files that are not needed anymore but they cause this issue with Outlook Express.
It might not be very easy to delete them since there could be thousands. Have patience and delete every file.
Once you have finished deleting them, restart your computer and start Outlook. You should be able to see the content of any e-mail at this point.
If this method doesn’t give any result, you can always reinstall Windows.
“%temp%” also works on Windows 7 (type it in the search bar from Start), in case you want to clean your temporary files.