This one had me stumped for a while today.
I had to rebuild a clients PC and was attempting to re-install XP Pro. The install started fine but would error out with a message about "XP Pro installation cannot copy files from installation disk".
I restarted the setup several times and the error would come up with a different file each time.
After scratching my head I decided to eliminate things one at a time. I tried a different Cd...same error. I tried installing a different CD ROM drive...same error. I then tried different cables to connect to the CD ROM drive...again same error.
What fixed this for me was to remove all the RAM sticks and replace them one at a time. After process of elimination it turned out it was a bad RAM module. Once I removed the bad RAM the PC installed as usual.
Hope this helps