Exchange server/ push mail not syncing consistantly?

[Magicality]

I will show an example from my SERVER log files below. I edited my phone's IP to 127.0.0.1, my email to email@domain.com, my username to username and my deviceID to XXXX for security purposes.

Note the difference in the two lines: One sends the login credentials along (3rd field), one doesn't. This results in the first one syncing the mail (status code 200), and the second one getting access denied and thus no sync (status code 401).

127.0.0.1 - email@domain.com [22/Jul/2008:08:55:50 -0500] "POST /Microsoft-Server-ActiveSync?User=username&DeviceId=XXXXXXXXXXXXXXXX XXXXXXXX&DeviceType=PocketPC&Cmd=Ping HTTP/1.1" 200 - "-" "MSFT-PPC/5.2.1001"

127.0.0.1 - - [22/Jul/2008:09:05:48 -0500] "POST /Microsoft-Server-ActiveSync?User=username&DeviceId=XXXXXXXXXXXXXXXX XXXXXXXX&DeviceType=PocketPC&Cmd=Ping HTTP/1.1" 401 64 "-" "MSFT-PPC/5.2.1001"