[Closed] Updating Itunes has affected my PC! Help!

Since updating Itunes a few days ago, on trying to open certain things like Google Earth for instance I'm getting a box which says 'choose the program you want to use to open this file' & there's a list of programs to use, (non of which work on Google Earth) If I want to open Itunes it does the same but the Itunes logo is in the box, so it works. Same with Memory Map. It seems to be doing this on trying to open anything on the desktop.
I can't even do a system restore to the day before I updated but it aint working either.
Any ideas? Bearing in mind I'm a thicky with computers!