Some of your folders may have been corrupted--are there tons of messages in any one of the base folders ie sent items/deleted/inbox etc?
OE can't really handle much mail--if it's big you may see it 'loading'
the messages each time you open it. This makes it unstable too--causing the fault that you get.
Don't keep folders as subfolders of the inbox--this makes OE very unstable.
Try deleting files to see if that helps--if not you may need to rebuild the *.dbx file which holds the messages.
Find out where your store file is by going to options/maintenance/store file and make a note of the path to your store file. This is where all your messages are kept. If you navigate to it you'll see .dbx folders--ie inbox.dbx outbox.dbx etc etc.
Let me know if you need to find out how to fix them if deleting doesn't work as you will need to backup messages or you will lose them if you do the folder rebuild.
...cos we\'re travelling...at the speed of thought...UltraMagnetics