When computers don't work it's often best to check out the silly things that may be triggering the problem. The computer of a client last week seemingly went haywire after she moved it from one room to the other leaving it unplugged for a number of days. After initial set up she noticed that windows updates were no longer working as well as a number of other issues with programs and applications.
What she didn't check was that the date and time in the bottom right hand corner of the desktop had been reset to a time years before sending the computer into a state of frenzy. Something as seemingly insignificant then and pretty basic is very important when dealing with the registry and the way that programs act. Always make sure that the date and time are correct.