Hi,   I've been using IDL 6.4 (64-bit) for a while using my department's license on a machine with an intel dual-core processor running RedHat. IDL doesn't seem to be able to utilize both processors on this machine, my CPU load never exceeds 50% even when I'm running that takes hours to calculate (in my procedures, the CPU is definitely the bottleneck). When running long computations the CPU load will hover around 100% on one processor, and then at random times just switch to being 100% on the other processor while returning the first one to 0%. Is this limitation due to IDL? The operating system? Or do I perhaps need to put in something in my procedures to specify that IDL should use both processors? I'm about to get a new machine running on a rather fast quad-core CPU with both Windows and Ubuntu installed. I wish to purchase the latest version of IDL as well to go with it for myself. Should IDL be able to distribute the processing load across all 4 processors? Would there be any advantage in putting IDL onto windows or Ubuntu when it comes to utilizing all 4 processors?   thanks, Marko