Good to hear that you found the cause.
Had you been running any lisps, macros, VBA, or similar
Odd things like that can happen if you have been running a routine that didn't complete properly (or was poorly written).
Such routines will often change settings to do what they need to and then change them back when they finish.
So it becomes a problem if they crash or are terminated before they have changed the settings back (Or if they are poorly written and don't put them back).
Im intelligent enough to know that I dont know everything; but I'll tell you all about it anyway.