Then, they must have done this as they would not be up and running the software and getting COM errors. So, I think it's safe(?) to say that the "upgrade path not supported" is not the cause of the issue in my original question.

After 8 years with no issues, moved from Windows 2003 Web Server Edition to a full Windows 2003 Server. I now intermittently get these errors from one of our "in house" apps: Initiating xxx ErrorRetrieving the COM class factory for component with CLSID {xxx} failed due to the following error: 800703e6. This error resloves to: 800703E6 - "Invalid access to memory location" Since I have had zero issues previously, I am inclined to think this is an environment/config issue as opposed to a software bug (Woudn't it have manifested before?). The server is on a 32 bit machine. I have the latest 2003 service pack (2) I have not disabled DEP system wide. (Although, this may(?) be the solution?) Does anyone have anything I can try to resolve this issue?

1. Would you give more information on the "move"? What was reason for move? (Why not to move to newer version Windows 2008 R2 SP1?) 2. What applivations do you run on new server and what is the configuration of IIS? Regards Milos

The move was the decision of management and I have zero insight as to why they did what they did. When you ask "what is the configuration of the IIS", what, specifically, are you asking about? Version? Build? etc... Thank you very much for your time!

Upgrade path not supported, check this similar thread. Thanks

That's very interesting. They do now have Server 2003 installed and they are running software. If the upgrade path was not supported, wouldn't this be impossible? (Or..???). To my knowledge (and I could be guessing) for them to be up and running with WS2003 means they must have performed a clean install. Right?

Yes, you need to perform clean installation and migrated the web server data to the new system.