An elderly friend is using WLM 2011 on Win7. She complained that she can't open or delete some messages in the Inbox.

I checked this out with the messages in question.

When I tried to open the messages I got a WLM warning (black exclamation on yellow triangle) saying, "A problem occurred while trying to open this message. <new line> A problem has occurred. Please try again." with an OK button.

When I tried to delete the messages I got an WLM information dialog box saying "An unknown error has occurred." with an OK button.

I then moved the messages from the Inbox to another folder (which was empty). I could then delete them but still not open them.

I checked that other messages for the senders of the problem messages did not behave this way, that is, they could be opened and deleted normally.

What can I do to stop this strange behaviour of some messages?