CompuServe Messages

I have a 7 Mbyte DXF file that I was loading into 3DS4. After 40 minutes, it said "Not enough RAM for that operation" "continue". "Invalid file." "continue." Settings were layers, weld yes, unify no, smoothing 30. I tried it again with colors, weld yes, unify no, smoothing 30. Same 40 minutes, same problem, same error messages. I checked my ram usage using the "?" key immediately after this, and it said I have 63784 available, and used 6944 the first time, and 9208 the second time. I have been importing these files for a while with no problem. At least one other one was 6 Mbytes, and had no problem. This consists of many individual pieces of an assembly I will be needing in an animation. Nothing here was to be animated at this time, only used as part of the scene. Obviously, I will do this again with fewer pieces. But I am curious why it says "not enough ram", but it appears I have plenty. Any thoughts on this? Thanks, Dennis