Problem with starting the installation

[Petar Petrovic]

I've got the following problem:
I have a hard drive where I intend to install FreeBSD set up as a 
primary master, and one CD/DVD drive set up as a secondary master. When 
I start the FreeBSD (version 6.0) installation, I choose standard 
installation, install Boot Manager (because I have Windows XP on another 
partition), set up partitions and when I choose to start the 
installation from a CD, I get the following error:
Error mounting /dev/acd0 on /dist: Input/output error (5)
What is the problem and how can I solve it?