If you have a system where most users get timeouts on their pop3 accounts this might be the fix!
Install and open wireshark (google wireshark) and set it to filter to only pop3 with this: "tcp.port == 110"
try to login to the pop3 server with telnet like this:
telnet exchangeserver.com 110
user userwithproblem@exchangeserver.com
pass testpassword
list
retr 1
see if you dont get signoff message in wireshark you might have this problem. Its detailed in KB816896
Make this reg file:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\POP3Svc\Parameters]
"CheckPop3Tail"=dword:00000001
(REMEMBER a return in the end or regedit wont eat the file is its supposed to)
Install the regfile, and restart the pop3 service.
Try and get your mail again.
Hope this helps someone out there 