game copies hang up

[dagimpy]

i have a couple of games (quake 2 and coolboarders 2001) that start to run and then just stop. quake2 gets to the new, load game screen and then stops and coolboarder gets to the pal/ntsc selector screen and stops there. i get to choose an option then the screen goes blank and the cd stops spinning and there it sits. i dont have a mod chip, but i use ps-x-change boot cd for ps1.
thank you for any help you can give me.