Another possible reason is that you have burned the discs at too high a speed. Conventional wisdom from other traders I\'ve dealt with seems to suggest no faster than 4x. And yes, it can make a difference. I used to burn at 12 x, but only use 4x for audio now.
Also, don\'t do ANYTHING on your machine while you are burning audio CDs - even more than one or two BTs can mess things up as the software takes up memory.
Also the point about different brand can be important - try to use silver-backed discs, especially when playing discs in portable/car CD players. Or even change the software. Try a disc using a different burning software - BurnAtOnce is a nice, small, no frills audio/data program which rarely fouls up.