It really depends, does your Sega CD play regular games OK? If the answer is yes, try burning the games again, this time at a slower speed, 4x or under.
Alot of times, game systems can't read games burnt at a high speed too well, and this can cause problems.
If the answer is "no" try cleaning the lens and the discs and see if that helps.
Of course it *could* be that your model 2 is going out, this is unlikely, but since mine died several months ago I thought I'd mention the possibility, the model 2 isn't as well built as the first model (which I now have
) Or the CDX, it seems that the model 2's have a high demise rate