Working for support for an internet company, I have seen many similar problems. My first assumption is always to try the Microsoft support page first. If that dosen't give you the answer, there are a few things to try.
First, many run-time errorsin Outlook express (all versions) that occur while opening Outlook Express are caused by bad mail box files, usually the inbox. Search the computer for files called inbox.idx, inbox.mbx, and any other inbox files. Rename these files to inbox.id_, inbox.mb_ and so on. When Outlook Express is next opened, the inbox will be recreated.
*-NOTE: This will empty the inbox.
If this does not work, rename the inbox files back to what they were (this will restore the messages), then try the same thing with the outbox, then the deleted items and so on, until the error is resolved, or you have gone through all the files.
If this noes not work, there is likely somthing wrong with the program itself. Try reinstalling the program, or updating the version (without uninstalling the current version). Last, but not least, uninstall and reinstall the program. If you want to keep the messages, copy all the files you previously renamed to a different directory, and the back once the install is doneand you have setup the account.
It is also possible that Windows programs running in the background could cause this problem as well. press CTRL-ALT-DEL to see what is running. Close one program at a time then open OE. If one of these programs are causing this, try uninstalling it, or changing some of it's default settings.