System Crash

About 2 weeks ago I got a notification that an update was available for Fences.  I proceeded to got through the update process and much to my surprise my desktop crashed badly.  I was not able to reboot and after several attempts called my tech support and he had walked me through rebooting my computer by reverting back to a previous successful startup.  

Needless to say but I am now very apprehensive about trying to update your program again.  I am now getting the update nag screen but will not update unless someone can tell me how to avoid my previous issue or at least how do I get rid of the nag screen.