You know...I had that happen with every disk I tried to install FC6 from. Downloaded new isos...burned again, etc. I found out, if you try it over and over, it will eventually work. OR...If you don't pick ANY extra packages at all other than what is default. Basically just next, next, next through the install it will work. However, I only tried network installs and installs from .iso images on hard drive. I never burned all 5 cds to try it that way.
I finally wiped FC from all my PCs though. Yum is just horribly slow. And FC6 in general is very slow. Opening programs...etc.
I have moved to Debian "Etch" and WOW! I am truly impressed.
Example of speed difference in package managers... Test I ran: Yum has a gui front end called Yumex. apt-get has a gui front end called synaptic. In Debian, I can open synaptic and search for an application to install and get it installed and closed again before yumex even displays the list of installable apps to pick from. The two PCs are on my desk at work. Identical PCs. Same exact hardware.
I've rambled enough....