My discs cannot be read

I had recently bought new Wii games to replace the ones I had lost on Gamestop but the problem is that during the middle of gameplay, I get a line that says my disc cannot be read. I am not sure if it is the disc or not but if so I may have to return it. This sucks but everything else including my Homebrew works fine. Could there be something wrong with my disc or is my Wii screwed up somehow?

Disc could be scratched. This usually happens with mario kart. If the disc is scratched at a certain part it may cause it to stop working if you race on certain tracks. Try to remember where you were before you got the error and replay it to see if it is a problem with the disc.

I alreayd replaced the other one so thansk for help.