Thank you both for your replies.
In fact I am able to run the software in windows 7 64 bits without "any" problem, but something is happening that is causing the program to stop working and I need to do a system restore in order to get it work again (or a windows udpate will solve the problem too).
However, I have noticed that the program stops working after a period where i am away from the computer (for exemple during the night, or during the lunch). I have tried deactivating antivirus but it didn't solve my problem.
At this moment, I have also disabled all the "energy saving" options like turning off the harddrive and i am hoping that this is the source of the problem. If it works, I guess there is a very strange explanation on this subject.
By the way, that dancing penguim is hilarious!