It's from either a bad burn or a picky player, although it's almost certainly from poor burn quality. The usual cause is from a combination of: bad media and/or a bad burner, poor firmware with poor compatibility with the media, burn speed used. There are other possibilities but those are the typical issues.
What kind of discs are you using? What burn speed did you use? What is your burner model and firmware version? - To find out burner model, firmware version, as well as other info, download Nero CD-DVD Speed. Once you've downloaded it, you can also test the discs you've burned for readability and quality, as well as checking a disc's 'media code'. The media code will tell you who actually produces the discs, as most discs are not made by the brand name they're sold under.
Post the disc and burner info and we should be able to give you further advice.