I am having the same issues now.
-What version of osTicket are you using?
1.6 RC5
-What's your MySQL version?
MYSQL 5.1.39-community
-What's your PHP Version?
5.2.11
-What host do you use?
My own dedicated server: Windows Server 2008 R2
Tried running with both POP and IMAP, but still gives the same result.