OK, figured out I'd previously denied Imgburn internet access for whatever reason. Fixed, and upgraded. However, the burn button is still grayed out. I don't understand why though, because I HAVE done it before - from the same pack no less. I doubt 2/3 of a 3-DVD pack would be shiny coasters before I even mess up burning it. On a probably somewhat related note, DVD+R is the only format I have had success with even though I have one that should do both.

Trying a different disc from the same pack did me no good. It appears my computer is not reading the media at all, like it's incompatible with DL discs. I know it is for a fact though, because I have definitely burned one before.

Sorry this is so late, I haven't been home. Yeah, it's +R DL.

Also, recently successfully burned a single-layer DVD. So I don't think it's a hardware issue, just this computer being itself =/