DCOM between Win2000 and XP Permission Denied

I have a DCOM object that runs on a Windows 2000 server and every client that is Win2000 has no problem connecting to it. If I use a WinXP Client I get an "Run time error 70 Permission Denied" when connecting to the object. I have tried messing with Authentication and Impersonate level setting and no luck. I have set all the security options for the object itself just like the machines that work in Win2000. Every setting is identical on all machines except that the 1 client is running XP. Anyone have a clue what to do? Thanks in advance.