installation CD integrity check

[MSK61]

I'm trying to install PC-BSD 7.1.1 on my machine. I get an error message stating that the integrity check of the installer hasn't been verified(indicating that the installation DVD contains errors). However I calculated the md5 checksum for the DVD and compared it to the one posted on the download page and they matched.
My machine specifications are intel core i7-920, P6T deluxe asus motherboard, 6 GB DDR-3 RAM installed as 3x2-GB RAM chips, and LG DVD writer GSA-H55N. I've two hard disk drives, one 250 GB SATA and the other 200 GB ATA. I've disabled the 250 GB SATA drive(from the BIOS). The 200 GB ATA drive is connected with the same cable as the DVD writer, with the hard disks acting as the master while the DVD writer acting as the slave.
Appreciating any suggestions!