After installing .net framework 4.5.1, SQL Server Management Studio fails to connect to any database server. A reserved error is received.
This can be tested and proven on Windows 7 64-bit, install SQL Express 2012, open Management Studio and connect to a database server. It connects successfully. Then apply 4.5.1 and try again - reserved memory error occurs.
This still happens when upgrading SQL to 2014 Express.
A workaround exists, run command prompt as admin, then do "netsh winsock reset" however this requires a reboot. And also redoing periodically.