SQL Server Management Studio COM Error
NOTE: This is stolen from ServerFault.com. I have copied it here for a convenient source for those who might encounter the same error.
PROBLEM:
You have an instance of SQL Server running on a Windows Server 2008. But when you connect to the engine via SSMS, you get this error:
Unable to cast COM object of type ‘System.__ComObject’ to interface type ‘Microsoft.VisualStudio.OLE.Interop.IServiceProvider’. This operation failed because the QueryInterface call on the COM component for the interface with IID ‘{6D5140C1-7436-11CE-8034-00AA006009FA}’ failed due to the following error: No such interface supported (Exception from HRESULT: 0×80004002 (E_NOINTERFACE)). (Microsoft.VisualStudio.OLE.Interop)
SOLUTION:
unregister actxprxy.dll then reregister it
run regsvr32.exe –r c:\windows\system32\actxprxy.dll
run regsvr32.exe c:\windows\system32\actxprxy.dll
run these in a command prompt as administrator
REFERENCE:
http://serverfault.com/questions/10941/sql-server-management-studio-connection-fails-to-com-errors
or
run regsvr32.exe /u c:\windows\system32\actxprxy.dll
run regsvr32.exe c:\windows\system32\actxprxy.dll
If you’re using WIndows vista and std security and you get an error on the second command (re-registering the component),then try running your command prompt as administrator.
that worked for me.