[imp] IMAP toolkit crash

[hwahing]

Hi all,
I'm new to IMP. My IMP server running fine for few week. but today I found
the user couldnot login thru the browser.
I found the error message like below:-

Dec  4 11:51:25 pop3 httpd[2670]: IMAP toolkit crash: Unable to look up user
name

should I need to reinstall the whole program?
The system is running under RedHat 7.1, kernel 2.4.9

Please help

Thanks,
hwahing