Unable to use Outlook 2003 after using Outlook 2007

We have set up a couple of test systems with office 2007 professional on them for public access to get people used to the changes. One user opened email using outlook 2007, then was unable to open email back at his own PC with Outlook 2003. The error is:

"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 or programs and try again."

There definitely is system resources available as well as memory, so it looks like an internal looping error or something.

This happens on multiple machines with Outlook 2003, but he is still able to access email on the test machines with Outlook 2007, and also with Exchange web access. I have tested another account and it was able to successfully use Outlook 2007, then Outlook 2003, then outlook 2007, so something seems amiss with his account.

I have removed his outlook profile and recreated it from Exchange server and it still retains the issue. I have forcibly removed the .pst file from both the local machine and the server (we use roaming profiles) and then recreated the profile, but the issue still remains.

Short of removing his entire account, I'm at a loss what to do next. His email account is working, just not with the outlook 2003 client. His account is otherwise operating normally, no other errors are coming up. The problem seems to be something with his outlook profile, but removing it and recreating it doesn't fix the problem. Is there anything that Outlook 2007 does to a user account that is outside the outlook frofile ? Like a registry setting?

Any ideas welcome as this has been going on for a week.
Windows 2003 server running Exchange 2003 (ver 6.5 Build 7638.2 SP2)
Windows XP SP2 client with Outlook  2003 SP2 (Ver 11.8010.8028)
Windows XP SP2 client with Outlook 2007 (ver 12.0.4518.1014)
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check this, this will help you out:

You may receive a "Cannot start Microsoft Outlook" error message when you start Outlook 2003
VRBonesAuthor Commented:
The article seems to involve malformed .pst file designation on install. In this cae I am not installing or reinstalling outlook, I am using different machines that have different applications installed (some with Office 2007, some with Office 2003).  The user can use any Office 2007 machine and his account works, or use any office 2003 machine and his account fails. Other users can use any machine and their account works regardless of office version.

I can remove his outlook profile and load someone else's and it works under Office 2003. Re-attach the exchange mailbox to his outlook profile and it works up to the point of retrieving mail (or possibly getting folder information as that is not displayed either), then displays the error up above.
VRBonesAuthor Commented:
Unresolved, but irrelevant now that the whole network is now Outlook 2007.

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