I've had a very annoying problem with Outlook Express for the past several months and it has steadily gotten worse, just thought I'd share a solution.

After I would right click and Search using the Find Message Dialog, when I would try to open a message it would say

"Message could not be displayed"

"Outlook Express encountered an unexpected problem while displaying this message. Check your computer for low memory or low disk space and try again."

I found this advice from Bruce Hagen MS-MVP Outlook Express in a newsgroup:

Create user folders for storing old mail and try to keep the default folders as empty as feasible. (My Sent items had grown over half a Gig!).

Also, try to keep the User folders under 100 MB. I now have a Sent Items 2, Sent Items 3, etc. For my incoming mail I have "_done", "_done2", etc. I had already done this to some extent before seeing Bruce's advice, but it is good to hear that it is the right approach.

He goes on to say:
"Click on Outlook Express at the top of the folder tree so no folders are open. Then: File | Work Offline (or double click Working Online in the Status Bar). File | Folder | Compact all folders. Don't touch anything until the compacting is completed."

"Turn off e-mail scanning in your anti-virus program. It is a redundant layer of protection that eats up CPUs and causes a multitude of problems such as time-outs and account setting changes. Your up-to-date A/V program will continue to protect you sufficiently. For more, see:

"In Tools | Options | Maintenance: Uncheck Compact messages in background and leave it unchecked. {N/A if running XP/SP2}."

"And backup often. Backup & Restore:

Hope this helps someone!