I've got one remote user who continually gets messages like "Outlook is
trying to retrieve data from the Microsoft Exchange Server test.xyz.com." or
"Microsoft Office Outlook is requesting data from the server." The user has
Outlook 2003 SP2 with all current patches applied and is running in cached
mode. His mailbox is about 650 MB in size, and he's using a broadband
Internet connection.

I've read lots of articles and tried lots of things (like recreating user
profile and disable all add-ins) to resolve, but in this case I've only been
able to resolve the situation by deleting the ost file and then allowing
Outlook to create a new ost file. This process seems to work for awhile
(sync works great), but eventually the user either sends or moves a message
with a large file attachment (usually greater than 1 MB) and trouble starts.
At that point, Outlook has trouble connecting with the Exchange server and
gives the messages listed above. The only thing that seems to work is delete
the ost file and have Outlook create another.

Any ideas on how to resolve this issue?

I too have been having this problem. Now I've already been ripped on the
Microsoft newsgroup for doing this, but the problem started ever since I
installed ie7. Yea I know, installing beta software.....

I've tried to uninstall ie7 and tried a reinstall of outlook. It seems to be
happening when outlook request any information from the server. For example
checking the address book and sending mail. I have been wrestling with this
for some time and I can't find a resolution anywhere.

Thanks in advance.

Kevin