My wife’s copy of Photoshop was doing some pretty weird things.  It would go through all the motions of starting up and then just disappear, crashing with no warning or error code.  I tried several different things including disabling the spyware detector and anti-virus to no avail.  Then I did what I should have done in the first place, I Googled it.  I had it fixed in about a minute after reading this post.  It tuns out that the settings file had somehow gotten corrupted and just needed to be deleted.  Holding down Ctrl, Alt, and Shift will allow you to do this.  When prompted, just delete the file and Photoshop works again!  You’ll have to customize a few things over again but that not a big deal compared to it never working again.