I have a very strange problem.

When I work in V6I, I always save very often, always to different copies (the program is not very reliable...). So, in a certain scene I'm now in the 25th version and, suddenly, when I do just a normal preview test render, it crashes and the program exits. Ok, no sweat, I think, I relaunch the program and the scene. It crashes again on render. Ok, let me go to the 24th version, which was just fine and rendered perfectly before. But... surprise, now also this version crashes!... I go back to version 23... and 22... all crash! If I load a completely different scene, it renders just fine. Only that one doesn't. So, it's something in common with all the versions, I think, some temp file that got corrupted and it's used over and over again. So, I deleted all temp files and env files (from the environment folder), tried again... but the problem remains! Now I have hours of work in a scene that doesn't render!
Any clue?!
Thanks a lot!