Here's what I posted last year on this. Check the size of the ISO images. Should be ~600mb each.

For those having troubles with the CD's, it seems there might be a problem with the two ISO images located on the MMZ_TimeZone Documentation thread. The two ISO images located there (East Coast, West Coast) are only 182mb each in size. If you burn a set of CD's from this distribution, the CD's will activate load in the NAV system, but at some point you will get a "Error reading CD" message displayed. I successfully used the two ISO files located on the Mike-In-Orange thread and those two files burned and ran with no problem, each being over 600mb in size. I used just standard CD-R pre-formatted disks. I also have a Sony Lightscribe CD/DVD burned that I used to add a custom laser etching image of my car on the front side of the CD. Sweet! So if you are having problems, make sure the ISO images are over 600mb before doing any burning.