Error message while running OE6

"Outlook Express could not be started. The application was unable to open
the Outlook Express message store. Your computer may be out of memory or
your disk is full. Contact Microsoft support for further assistance
(0x80004005,183)"

I can continue to work in OE, the error displays in a separate popup window
that will be behind the other active window. Closing the error message
results in it's reappearance, either immediately or within a few seconds,
sometimes as long a minute.

Operating System is WinXP Sp2, all updates. McAfee Viruscan V.12.0 is
installed but all email intervention is turned off. Maybe I should
uninstall it completely to see if the problem goes away??? Problem started
occurring in the past week or so, McAfee has been on computer for several
years, new version for two months.

OE Inbox folder is pretty clean, only a few messages. Deleted Items folder
is empty.

Any ideas?