Thanks TulsaRose but this has nothing to do with our issue.
It's actually an outside client that reported the issue. She sent me the invite and it didn't work for me either, same error. I sent it home where I have Outlook 2003 and it opened up no problem. It's an OL 2007 + issue.
I have tried the Add-in Manager, Anti-Virus and file association but none of them worked and I can't find anything worthwhile on the web. I have posted at Tech Republish and CNET without any results. My friend uses this site so I was hoping one of you Gurus would have the answer for me.