Our environment: Exchange 2003/SP2. We have been using the Cached Exchange
Mode for a while without any issues. We have run into a problem when using
the Cached Exchange Mode:

“Cannot start Microsoft Office Outlook. Unable to open the Outlook window.
The set of folders could not be opened. Out of memory or system resources.
Close some windows ot programs and try again.�

If we take it off the Cached Exchange Mode it works fine.
Tried many many things, including removing the virus program from the XP/SP2
box,
applying all the Windows and Office updates,
trying a different PC,
starting Outlook in the Safe Mode,
moving the OST file and completely recreating it…

any advice will be greatly appreciated, I am stomped!

In case somebody wants know
After 3 hours with Microsoft Support - here is what we came up with...
Problems with the Cached Exchange Mode (CEM):
Make the profile Roaming…
Open Outlook in the Online mode (NOT CEM)
Export to a local file such as C:\temp\User.PST
Quit Outlook
Go to Exchange Admin and remove the mailbox and run the cleanup agent.
Go to Active Directory Users and Computers and start Exchange Tasks and add
a mailbox for the user.
Go back into Outlook and import the file into the NEW EMPTY mailbox.
Quit Outlook…
Delete the Mail Profile (IDOC.PRF)
Create a new Mail Profile(IDOC.PRF) and use the Cached Exchange Mode – make
sure the OST file is pointing to the right location.
Make the Profile Mandatory…