Hi Carlos,
I have been running an expired demo of RED 5 for quite a while now and have the same problems as you do. I did mention this problem months ago over at BorisFX Forum for which they said they would investigate about my problem but never got any feedback.
If you are inside RED 5, it will crash when Vegas autosaves. Then your .veg gets renamed to .veg.tmp
Unfortunately I have given up on RED 5 as this made RED 5 unusable.
Here is the link to the thread I started:
http://forums.creativecow.net/readpost/15/863102