The problem has already been described but here it is outlined along with some sample code which produces the problem on my machine.
The backspace and delete key do not work on all occasions. There does seem to be a workaround whereby selecting the text and pressing backspace or delete will work.
In this code snippet the problem seems a bit sporadic. Anything below line 7 the backspace won't work but everything above it does seem to work. I'm beginning to think the problem has nothing to do with comments but perhaps it's related to line endings or something else.