Search Problems in Outlook Express

I have OE6 on Win XP. Sometimes when I use the "Find" facility, I get a list of the emails that satisfy the search criteria, but when I go to open them, I get this error message:

"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 don't have low memory and I have vast amounts of disk space. If I note from the search results the dates of the messages of interest, I can close the search window and go to the appropriate email folder, find the email of interest and open it from there OK. Very tedious.

If I restart the computer, the problem goes away for a while, but it will return within a few hours. It can happen regardless of what email store folder I search in.

When I had the same problem on a previous computer, it was suggested that the folders were corrupted. Nothing I did got rid of the problem premanently. I thought the new computer with new OE would sort it out, but the problem has jumped computers to haunt me.

All suggestions gratefully received.

Alistair