I am having the same problems, but in my case it all seems related to registry access.
I wasn't the one who setup SQL Server 2005, that may be part of it. I am, through group permissions, a local admin on the (virtual) machine. The error I see, when simply starting the "Management Studio" is:
"System.UnauthorizedAccessException: Access to the registry key 'HKEY_CURRENT_USER\Software\Microsoft\Microsoft SQL Server\90\Tools\Shell' is denied.
...(and a whole bunch of other message info...).
I was able to run regedit, find the user tree that did install it, I exported the entire MS SQL Server branch out to a file, edited the file, and changed the specific "user" reference to "HKEY_CURRENT_USER" and tried to merge it, but again, access was denied. So it seems that my problems are related to the registry and access to it, or not in this case. Maybe I should try a different login...