DVD copy issues

I was using "Easy DVD-Video Copy Pro" to back up my DVDs, which used to copy my DVDs without any kind of problem, but lately it just doesn't want to work anymore. Whenever I try to copy a DVD, the copy process works just fine, but when I go to burn the DVD, after about 20 seconds it spits the blank DVD right back out telling me the "process completed successfully" when in fact it hasn't even started burning yet. And it does this no matter what quality DVD I'm using (I'm still using the same Brand I've always used, but I've also tried more expensive brands, no change).
When I emailed the support people, their suggestion was to try and use another program, Easy DVD Clone, and when I try to do that, again, copying works just fine but when I go to burn the disc, I get the following error message:

Writting failed, exception 8, status 31, text
'CStarBurn_ScsiTransportASPI::ExecuteCDB(): Command failed'

Is it my DVD drive? Other DVDs (regular data DVDs) and audio CDs burn just fine, its only when I'm trying to burn DVD movies that I'm having problems.

FYI - I am using Windows Vista Home Premium, never had any problems so far with it.

I'd really appreciate any help you can give me!
Thanks!