I do thank you so very much, it works just fine now
Problem is with F-secure - How to:
Are you using F-Secure Internet Security 20XX?
If "yes", try the following:
Go into the options menu, put the program into the exception list of the real time scanner of F-Secure. The problem with F-Secure and error code 51 concerns many games, also Toki tori.
All you have to do is to add the entire "Dungeon Siege III" folder and that