I Think I'm Narrowing-in on the NEO-HD problem
 

After several re-installs and after being suspicious of Nero and AV programs I now believe I have narrowed in on the NEO-HD "Vegas Stopped Working" issue. I confirm that the avi files are being corrupted, but NOT IN THE CONVERSION but by copying within windows.

I base this finding on this test:
I format my SxS card and shoot scenes which I convert with NEO-HD to avi from the card directly to my hard drive (no ClipBrowser installed) and then open these files in a new Vegas project. No problems.

Now I take some of those clips and copy them back to the SxS card, or I save them directly to the SxS card in the first place rather than to my hard drive, and I then bring them back into Vegas or start a new Vegas project with them and the project dies. I think the SxS driver may be suspect or maybe even the cards! This ties in with the workaround that captures with ClipBrowser and then convert to avi within Vegas.

Wow! Interesting find.

I've found that if I do ANY operations on the SxS card, other than "copy", without using the ClipBrowser, the card is corrupted, I get an error message from the camera and have to reformat it