I think I've found a bug in ImgBurn.
I was burning a DVD from an ISO image. As as I was doing some other i/o intense operations, at some point my hard disk did not keep up with the burning process. ImgBurn then halted the process, while displaying that it was waiting for the disk activity to reach a target level (which was marked as 1). I waited quite some time (while disk fluctuated between 0,5 and 50), in the mean time having shut down all my other programs that might cause additional disk activity.
After some time, I checked out what was causing the disk activity. The permance monitor then told me it was ImgBurn itself, reading my ISO. As it was not filling up any more buffers (in the program, not my hardware buffer), this seemed to go nowhere, so I had to cancel the burning process, and discard the DVD.
I you don't mind I have not tried to reproduce the situation.
My specs, if applicable:
8 speed blueray/dvd burner (Optiarc)
Vista Ultimate x64
4 Gb RAM
Intel core duo 2GHz
Hope this helps. Thanks for a otherwise great and friendly program!