Nasty Burning and Disc Recognition Error(s)

Question

Hi there,
I've recently been having two problems with my drive (HL-DT-ST DVDRW GWA4080M model) regarding DVD-R burning. I work with Toast Titanium 7. I also recently tried a new brand of DVD called Dataware (I switched from Ridata, with which I had no problems, but I doubt this is a DVD compatiblity problem).
Problem 1.
My drive doesn't recognize blank DVD-Rs. When I insert the disc, it spins for 20-30 seconds before ejecting, when I've got it set to open Toast when blank is inserted. And when I manually open Toast and insert the disc afterwards, in the 'Record' window, it says 'Waiting...' rather than 'Blank DVD-R'. Again, this occurs for 20-30 seconds before the disc is automatically ejected.
Problem 2.
On the off occasion (like once in every 10 or more blanks), the disc will be recognized and the burn will begin. Midway through, I get a pop-up along the lines of:
The Drive Reported An Error:
Sense Key = HARDWARE ERROR
Sense Code = 0x44, 0x86
INTERNAL TARGET FAILURE
That's the most recent one; I used to get 'Section ____ is unverifiable' in the verification portion of the burn. But I've had that a few times when I've tried backing up some of my oldest discs that had some scratches, so I didn't really worry too much.
This message leads me to think my reader/writer aren't contacting my discs properly (hence why it can't recognize blanks often), and when it does make contact, it loses its place (maybe why it can't keep burning). Is this possible?
I've run the Apple Hardware test for diagnostics on my hardware - it came up fine, but I'm going to try it again, just in case.
Any suggestions would be immensely appreciated! I'm a university student (one who tries to take very good care of her computer, I should note - I even check any discs before I insert them to make sure there's no dirt or anything), and have papers and notes to take (my degree goes right through summers), so the prospect of having to send my MBP away for several weeks for repair is far from appealing.
And to note, I've never had a problem with it before; I've had it since last September.

Answer 1

Most of the time, when I have a problem like this, it's because of the actual disc being used. Though they may fit under the required 'specs', being DVD-R or DVD+R or whatnot, some burners just don't like some discs.
A while back (this was at least a couple of years ago), there was a post somewhere that listed where each seller got their discs from before relabeling them as their own. There are some discs that are just made with higher quality, more consistently, and those will rarely give you problems.
Anyways, I would always try to test out a different kind of disc in my drive to eliminate that problem first, as for my experience, those kinds of errors have almost always been caused by the disc and not my hardware.