This is a real bad news i hear now from the group as i always reach this bug with the C3 version (i do heavy scenes !!) . My first concern to upgrade to CS4 was this bug i expected to be corrected. I have 2Go RAM, and the bug occurs before than the whole system reach this limit ! My opinion is that it related to HRDI rendering most of the time..but bad bad bad news for the CS4. I've been in contact with Eovia support a few month ago for that bug (that they told me have reproduced) and it stills there ???? Nothing more frustating than spending days in texturing, modeling, setup lights / shadows and so on, and when you ask for the final render with good parameters, then ALWAYS come this infamous message " a memory allocation has occured".... This news definitely spoiled my day :-(((