GUI malfunction

I connected to my friends wireless NetGear router and when qued to set password, my computer froze. I restarted and when I logged back in, my background had been set back to default. I know that it may not be a big deal but its still something I would like explained. I just started using my Ubuntu box and have not any problems with it till this. If anyone has any input as to what could have happened, that would be awesome. Thanks...I know I may sounds stupid, but I'm ok with that.