BAD SITUATION

HI,
Ive got a big problem, i gave my friend a copy of army men sarges soldiers and this was his first dreamcast backup he ever used. When he put it in, it went to the menu screen and a message popped up saying "insert disc" the screen then freezes and now he can't play any dreamcast games, original or backup. I'm just wondering has this situation ever happened to anyone or is it just something wrong with his dreamcast. Is there anyway to fix this problem. Thanx to anyone who helps ahead of time