Then follow some of this advice, especially the first one.
The following is quoted from....
~Robear Dyer (PA Bear)
MS MVP-Windows (IE/OE, Shell/User, Security), Aumha.org VSOP, DTS-L.org
[[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 [N/A 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 attempt to close OE via Task Manager or shutdown your machine if
Automatic Compacting is taking place (WinXP SP2 only).
- Your anti-virus application's email scanning feature can also cause
corruption. Disable it. It provides no additional protection. ]]