Based on what you have described, the likely cause is something in your Window Layout.
Issues like this can be caused by changes in Windows to graphics drivers, new monitors, changing plugs on your graphics card. This kind of thing is noted here,
http://isboxer.com/wiki/HOWTO:Tweak_you ... er_changes where it says:
Recent Hardware or Driver changes
If you have a new computer, graphics card, monitor, have moved some cables around, have recently updated graphics drivers, or upgraded/reinstalled your OS, or copied this profile from another computer, then you may need to make a new Window Layout. The aforementioned things can cause the internal Windows display references to "shuffle" around, and it makes your old Window Layout try and present to a physical display which is no longer connected to the same internal virtual port. Windows can accommodate this, but usually at the expense of FPS.
It is possible that Key Maps or Clickbars could also cause a lockup problem, but this will generally only happens if you have some kind of loop in your configuration where a mapped key calls another mapped key which calls the original mapped key (this may continue round and round, or potentially have some kind eventual exit condition).