PI 3.02 crashing, mis-rendering alphas

Hi, Have been using PI for about 3 years now. It's a great program, useful for all sorts of things. I've just updated to V3.02.

I have a commission for doing a series of explosions and effects. They are simple explosions and smoke effects, rendered to .png format. The files are all done, I just need to render. Some of the ip3 files render fine. Some of them are 'problem files' which seem to have the following issues:

1) Alpha channels aren't rendering correctly: the files render out, and the RGB is visible, but the alpha is 'sheared' like it's been stretched diagonally, and no longer aligning w/ the RGB. It looks like tiger stripes. This happens w/ .png and .tga files. Have been trying turning off every possible feature, but it still seems to happen.

2) Program hangs, or just suddenly crashes AFTER render. Either way, the program does not recover after a render. If it suddenly crashes, it happens when switching to another window, such as explorer.

If you would like, I can email an example file, or post examples of what is happening. Any help much appreciated! If I can't finish this project I'm going to lose this commission and earn the ire of the art director! Not good!

I have a Geforce 7800 GTX graphics card, with drivers updated just a few days ago. Performance is very fast, even w/ motion blur cranked way up, or on large files. I'm running Windows XP, media center edition, SP 2.