Without specifics, it's tough to nail anything down...see the help thread here, note post #13. We'll need details for specific responses.
Generally, issues such as you describe are the result of: poor quality media (this includes compatibilty issues, both with your burner and player) and inapproriate burn speeds (usually too fast), or a combination of the two.
The most recommended SL blank media on cdf are Verbatim and Taiyo Yuden. This doesn't mean all others are crap, however. Also when posting media, please try to post the MID (media id). you can find this with utilities such as nero cd-dvd speed and dvdinfopro...both are free and very useful tools.
Hope this helps.