Cant burn with Lite-on sohw-812s

Hi all, I’ve just recently been having a few problems with my Lite-On DvdRw sohw-812s, my problem is that it will not let me copy onto a - media, When i first bought the item it came with a + and - dvd media disk, these worked perfectly. since then i got 5 DVD+RW to back up my media. but today i decided to get some more and I got some DVD-RW to back up my movies and music, but when i insert these DVDs it takes a moment to acknowledge the DVDs and when it does it will not let me write on them. it just freezes my software.

I’ve read some of the other problems on this fourm and I have updated the Firmwire, and the Aspi, but i still have the same problem. I have writen down my specs at the bottom, but not sure if that will help. as like i mentioned above, when i first got it it worked on - media perfectly, but now it will not.

Please help me, as i am in need of backing up my software, and dont want to have wasted my money on these DVD-RW.

my system specs

AMD Duron 1.6ghz
512mb Ram
60gb Maxtor Hard drive
256mb Gefore FX 5700LE
Sony DVD-Rom DDU1621
Lite-On DVDrw SOHW-812s

running Windows XP Home

More exact info on the media please, because your burner will only accept some -RW media and also deny working with crap ones…