Class only registered when accessing as Administrator

Question

I am trying to access a COM dll from my .NET application. That dll is registered using regsvr32. When the appication that tries to access the dll is running as a normal user the application quits with: class not registered. But when I start the application as Administrator the access to the dll is fine. As far as I know registered COM dlls should be available on the whole system no matter what priviliges the user has. I have an older version of this dll that can be registered and the application works even without Administrator rights, so I assume something in the dll has changed. Does anyone have a clue what could be wrong with the never version of the dll?

Thanks in advance