Hi phil,
the problem occured on all our system, the headnode and x32, x64 client computers with the client utlities only installation.
Fortunately I just got an Email from Mark Ihimoyan from Microsoft which solved the issue after two weeks of investigation.
Her is his Email:
Ok.
I think I found the solution to your problem.
Look at this blog entry:
http://blogs.msdn.com/jchiou/archive/2007/11/23/vba-managed-code-dll-automation.aspx
Now I know you might not understand Chinese but it does point to the KB here: http://support.microsoft.com/kb/908002/en-us
Also some indications of people running into similar problems can be found here: http://www.thescripts.com/forum/thread489569.html
It would be worth it to install the fix in the kb and let me know if that solves your problem.
Thx.
Regards,
Johannes