Outlook Express - Can't Change Email Account Name

I have several email addresses (accounts) and have always been able to change the name of the account whenever I want (via account properties) - not the display name for the "from" line, but what I name the account. But now, if I try to change it, it won't keep the changes and reverts back to the name it was before. I've only recently gone to WinXP SP2, and am wondering if it's something to do with SP2?

Would anyone know how I can fix this please?

TIA
(PS - I'm fairly experienced in OE ).

 

I thought I'd try deleting and recreating one of the accounts as a test, and it naturally worked. However, if I then try to change the account name again (as a test), it's the same problem as before. Therefore, something somewhere must corrupt?