Originally Posted by kbp
You don't need to use the iso from Technet, just copy the sp3 exe onto any cd - the installed result is the same.
As stated, I had similar problems with other DVDs and CDs, including data CDs that are backups of installers and so forth.
The problem was as Jefro said...the DVD drive was too old (12 yrs?), and easily confused by homemade CDs and DVDs. The new DVD drive can read all of CDs and DVDs the original drive couldn't read.