please make vray more stable when it comes to memory problems.
i think the user should have at least a chance to save the project but right now when max or vray gets out of memory (i have 1.5 GB by the way) there is a 80% chance that vray crashes max to the desktop.
i think its an vray issue and not a max isseue because it happens on displacement calculation with large maps and i get a vray error message before crash.
Your problem could also be a bad ram dimm. I had a similar problem with large renders, smaller scenes were fine but as soon as max/vray needed to use the extra ram it crapped out. Some times I got errors and some times I didnt. I ran memtest and found/replaced the bad stick and all has been good since.
It may not be the issue in your case but there may be a slim chance that would cause issues
-dave
no my ram is 100% ok.
it´s an vray error.
it happens on big scenes only, right, but i can render even larger scene with MR.
it has something to do with the displacement calculation and maps around 4096x4096 pixel.
ah, k just a thought 
-dave