It's important to know the Details.  When you get "encountered a
problem" message, there is usually a  "click here" link to see the error
report.  When you click on the link, it will give a message that will
list the Appname XXXX and Modname YYYY.  The XXXX and YYYY are important
to identify the cause and solution.  You can ignore the rest of the
message.

For further help

Use the following newsgroup for questions or problems with OE6
news://msnews.microsoft.com/microsoft.public.windows.inetexplorer.ie6_outlookexpress

You will find out information about issues affecting Outlook Express 5/6
at:
http://www.oehelp.com/
http://www.geocities.com/SiliconValley/Bay/6386/IE_ng_notes.htm
http://home.attbi.com/~jimpickering/
http://www.insideoe.com/
http://www.kellys-korner-xp.com/xp_oe.htm

For best results, use the "msnews.microsoft.com" news server for reading
and posting messages regarding help with Microsoft products.  This is
the news server that most of the regulars use.  You'll get more timely
messages, and miss fewer of them.  News messages often take days to
wander from server to server, and often get lost.

To set up an account for MSnews in OE
http://www.insideoe.com/resources/communities.htm#setupmsnews

[x-posted of OE General]

You're running Windows XP, according to your headers, not Win98.  Please
post any new questions, not replied to this thread, in OE General newsgroup.
The following link will open OE General in your newsreader using the free MS
newsserver:
news://msnews.microsoft.com/microsoft.public.outlookexpress.general

How many messages are in your Inbox?

How often do you manually compact all OE folders (cf.
http://www.insideoe.com/files/maintain.htm#compact)?

Is McAfee Site Advisor installed?

General OE Caveats:

- Don't use Inbox or Sent Items to archive messages.  Move them to local
folders created for this purpose.

- Empty Deleted Items folder daily.

- Disable Background Compacting [not available in SP2] and frequently
perform a manual compact of all OE folders while "working offline".  More at
http://www.insideoe.com/files/maintain.htm

- Do not cancel Automatic Compacting, should it occur, and do not attempt to
close OE via Task Manager or shutdown your machine if Automatic Compacting
is taking place.

- Your anti-virus application's email scanning feature can also cause such
corruption.  Disable it.  It provides no additional protection.