A fatal error has occured in Outlook

[Eric]

I cannot send or recieve (POP) in Outlook.

I can set up POP accounts and they test okay. But they
don't really work.

This is one of the symptoms. When trying to change the
Send From Account "Unable to complete the operation. A
fatal error has occured in Outlook".

I can recieve if I set up an account as IMAP. I can send
and recieve POP accounts from Express.

I've have run detect and repair.

I have reinstalled Office XP.