K7S5A Pro 5.0 + LG gsa 4167B

I installed a LG DVD burner(GSA 4167 B) in my sister’s computer, this isn’t the first I have installed, and I updated the firmware too. The burner will read CD-r’s and it will read store bought DVD’s. It will not read DVD-r burnt movies and will not read Store bought movies using any dvd and clone dvd. I change the IDE cable. I know the burner work as I saw it work when I took it back to have the guy at the store check it out. Any suggestions. The salesman suggested I reformat the hard drive and start with a fresh windows XP.

Thanks
K7S5a-Pro 5.0 Motherboard
AMD 1800+
256MB ram