Hi. I've had this issue occasionally and I'd like to share from my experience.
Before fiddling with the buffer size there's the following to try:
1. Restart computer. 99% of the time the issue goes away without the need to touch any settings.
2. Close all other programs especially if they take up a lot of ram (even if you still have lots of ram available). Works most of the time.
3. Enable the swap file. If you've disabled the swap file because you think you have enough ram remember that some windows apps behave eratically if you don't have the swap file enabled no matter how much free physical ram you have.
I wonder if this is specific to running Imgburn (a 32bit app) on 64bit systems since I've noticed the issue can be made to go away when one frees ram under a certain level (less than 4GB physical used). It would be interesting to see if such an issue would still exist on a 64bit version of Imgburn.
I for one I am thankful for the big buffer available. It makes me feel safer when writing simultaneously a DVD (internal drive) and BD (external) having as source an external USB HDD. Not kidding, see attached images.
A word to the developer: I'm a few years late but ... thanks for this great program
