Hi XX,
You're right, I've cleaned the slot and it's working, I didn't think that it was a dirty slot because I tested at least 10 games before the MS5 and all of them worked and after it I tried with a MS2 and it worked too, and the same situation with another mv1a, so I thought that the problem was the MS5 itself. I cleaned the slot in this mv1a too and it works.
Thanks a lot
Saludos