I often burn copies of CDs to keep in my car for my listening pleasure. However, I bought some more blank CD-Rs recently, and I thought they were the same kind that I had normally used, except these new ones will not play in my car's CD player. Is this because of the CD, or because of the CD player, or a combination of the two, or neither...?

Kirby -
You may have gotten rewritable CD's instead of the permanent ones.

These are formatted differently from the permanent ones. The computer can play them, but most CD players are not set up to read them.

They are good for storing info for the computer, or for temporarily storing files if you need to recover your hard drive.

The problem with most CDR (and CDRW's as TIE pointed out) is that they are 'lighter' than regular CD's. CD's are read by bouncing a laser off the surface of the CD. On the CD are light spots and dark spots, representing binary 0's and 1's. This in turn is translated into the music you hear. However, with burned CD's, the dark spots are usually lighter than a professional grade CD. This can cause problems for some CD players. CD-RW's are particularly prone because they are even lighter than CDR's. Even if what you bought are just CDR's, different disk can have different results. Also, sometimes the color of the disk comes into play. I've seen CD players that only play gold CDR's, and won't read the blue ones. You may have to try a few different brands before you find one that will work in your car.

I had been thinking that the problem might be the color of the disc--the first ones I got were blue, and these, although they're the same exact brand and everything, purchased at the same place, are gold/silver (can't really tell with the lighting in here). Thanks for your help!

Burn them at the slowest speed and all will be well!