Oh god, that old crappy bug...man, I should just release the temp version I made damn near a year ago. It had that problem fixed as well.
Hmmm... this stuff could have happened, when you used pen pressure on opacity with brush #9. OpenGL didn't like tiny movements for a line (within a pixel) which has to blend between different alpha values from start and end point (both being in the same place). It freaks out and creates this negative alpha values that were sending Verve into a minor tantrum. I'm not sure anymore what I did to fix this in a painting, but there was a way. It might have been with layers, like adding a layer underneath and laying down some paint behind those places and then merging or so... or a layer above and merge it down... I just forgot.
However, future versions will not have that stupid problem anymore. I'm really sorry about the mess you ran into.
Again, the issue is related to pen pressure on opacity, if I remember correctly. And it's movement related then. Since only very specific circumstances can make this happen, it's something you can kind of avoid right now, but it's really a shame...

...grrrrr...I might have to do a stupid release, which I wanted to avoid, but it would certainly be nice of me. So many things I had fixed, including saving large images and I believe a few minor compatibility things with other card vendors (Intel and AMD).
I'm too busy right now, though... maybe in a few weeks.
