I just spent 30 minutes on SSMS which hanged on me every time I tried to launch it. I searched the Internet but couldn’t find a solution. The SMSS process was heavily using the CPU and slowing down the machine, but after the splash screen the SSMS application window wouldn’t appear.
Then I downloaded Process Monitor, saw that the process was continuously using a file called C:\Users\username\AppData\Local\Microsoft\SQL Server Management Studio\11.0\1033\Ssms.CTM.
I killed the SSMS process, renamed the Ssms.CTM file, and launched SSMS again. Problem solved!