FreeBSD 7.0 installation problems.Please help!

[kjk tttytyty]

Good morning!
I was installing FreeBSD 7.0 i368 using the downloaded from ftp.freebsd.org ISO images.(I've downloaded 3 main CD's without LiveCD and LifeFS)
While installing it gives me some errors :

"Write failure on transfer!
(wrote -1 bytes of 1425408 bytes)"
"Unable to transfer the GENERIC distribution from acd0"

When I tried to boot the system the loader says:
"Couldn't extract kernels"

I have a bit of experience with Linux systems but I can't understand what I've done in a wrong way with FreeBSD

Can You tell me what's the problem with my installation?
How can I successfully install the FreeBSD OS when I have that errors?

Thank You very much.