DVD, Cd-R Problem Help Please

Here is an odd problem.
I have a creative 12x PC-DVD drive. And then I bought a Sony Supressa 16x cd-r/rw drive. And now my dvd's wont work. When I try to play a DVD my screen freezes and goes black. Some times it will be a black bar on the left side of the screen, some times the whole screen goes black with little green lines at the top of the sceen. And another thing is, both CD-ROMs dont want to copy to the hard disk. They will install programs, but when I try to drag and drop, it gives me a weird error message. Its really making me mad,I bought like 6 dvds and now i cant even play them. Any one know a solution. Feel free to email me if you have any ideas. I have tried all diffrent drive positions, switching drives from slave to master, and nothing seems to help.

AMD Athlon 600mhz
512mb ram
maxtor 20gig hd(primary master)
Western Digital 40gig hd (secondary master)
Sony Supressa 16x/10x/40x CD-R/RW (secondary slave)
Creative 12x ovation PC-DVD Rom Drive (primary Slave)