I have been getting the same error, with "Access denied" as the reason. I click on 'Continue' to go ahead with the burn. I have created as many coasters as I have usable DVD's. The last one failed the verify process at 99% - so close, and yet so far. I have tested the ones that failed to verify, and they are indeed corrupt.
I never had this problem before when using XP Home and ImgBurn 2.4.0, but now am using a laptop instead of a tower, Windows Vista, and ImgBurn 2.4.2.
I have checked for firmware updates.
I get the same error and create coasters regardless of my media (have tried Maxell, Memorex and Verbatim).
I have read the FAQ, and every forum thread I could find, with no success.
I tried Process Explorer, which I have used for a long time, and found only ImgBurn when I searched for cdrom, and found nothing when I searched for the drive letter.
I tried using Unlocker, as suggested by Jill in one of the threads. Still, only ImgBurn showed up as having control over the device.
I even tried searching the registry itself for something blocking access or control.
In Process Explorer, I scrolled down through the processes looking for anything that even remotely looked like it might have a grip on my burner. I found two processes related to the HP QuickPlay program for watching DVD's, and found two processes related to MusicMatch. I killed them all.
I even opened up the Windows services manager and stopped any file indexing services, thinking they might be accessing my burner.
I still am getting the error after following a lot of suggestions, and trying several things on my own. I like to think of myself as pretty smart where computers are involved, but I am at a loss on this one. Frankly I suspect Vista is at the heart of my problem, but I can't for the life of me figure out how or where. Any more suggestions would be welcome.