Are you using any IDE extensions that use standard DLLs?
Do you have anything setup to automatically reference specific imports for a new project (eg. a
modified template)?

My advice would be to first try reinstalling (or repair) VS.NET. If that fails then take a disk
image and try uninstalling SP2 to see if that resolves it. I'm not suggesting this as a long term
solution but merely as a means to determine if it's SP2 that is causing this issue.

This error:
'System.Runtime.InteropServices.COMException' occurred in Unknown Module.

Definitely implies that a standard DLL (eg. not .NET based) is being instantiated (and failing).

This error:
"An unhandled exception of type 'System.ArgumentException' occurred in
Unknown Module.

I'm not familiar with and can't really comment on.

You did say when you try and *run* a project in the original post - do I take it that this now
exhibits itself when merely creating a new blank project? What type of project (language and type)?
Check the references that exist for the new project and inspect the application folder for any
<something>.interop files - they should point you in the right direction to finding the culprit DLL.
If you run it in debug does it break out at a specific line?

Chris.

That's the thing that I cant get my head round.   I am using no COM objects
or calling any functions - even when I start a blank Windows Application
project, the dreaded message appears.   Yes, I am using SP2!!!!

Any ideas of how to fix it?

Neil Brown