That sounds more like some defect has happened to the drive. I really doubt that updated firmware would correct the problem since the drive originally worked ok. Is the drive still under warranty? If so, I'd suggest you return it for repair/exchange. If not under warranty, you'd be best to just replace it. However, if you're able to find updated firmware, go ahead and try it as you have nothing to loose.
I have a BenQ DW1650 that's suppose to burn any media but refuses to burn dvd-r disks. Even with an updated firmware it still refuses to burn dvd-r (even high quality Taiyo Yuden). So I'm in the same boat as you. Mine is not under warranty so my only choice is to replace it.