problem with gta san andreas back up

[drisky9]

i've recently backed up my san andreas, the game works fine but every so often i get a black screen saying 'problem reading san andreas disc' and then it'll start playing again - i've tried backing this up a couple of times on different discs and different software but each one does the same - any ideas? this can be really frustrating i can be in the middle of doing something then this screen will come up and next i know i've been busted!!!!please help.