I had installed SQL Server 2008 R2, the installation was succesful. But I can't open the Management Studio because this error is shown: Package 'Microsoft SQL Management Studio Package' failed to load. I'm using Windows 7 Professional SP1 32 bits. Any idea? Thanks.
First check your shortcut, make sure it's C:\program files... and not \computername\C$\program...
Second try a reinstall via: start /wait :\setup.exe /qb REINSTALL=SQL_Tools90 REINSTALLMODE=OMUS
If thats not the issue have you changed any .Net permissions? Have you tried reverting them back?