I had the same problem since I installed latest windows update (Windows 7 Home Premium).Skype, Winamp, Windows Desktop gadget, AVG and Malwarebytes all crahed upon startup.
I uninstalled the last windows update after trying dozens of other options posted in forums - this solved all my problems. The update that caused this was kb2670838
Not sure if this compromises security of my computer though, and how it will behave after installing next update.. any thoughts?
Mod Edit: Split from http://www.bleepingcomputer.com/forums/t/492482/multiple-programs-stop-working-upon-launch/. ~bloopie
Edited by bloopie, 05 May 2013 - 01:16 PM.