I'm not to familiar with my iMac, although I am a IT Professional when it comes to PC's. Every now and then my iMac hangs, usually when using my web browser, and especially using a download prog., like LimeWire. I also get some memory error messages, but since then I've add more RAM and adjusted my virtual memory to 2 times the amount of my physical memory, (192 MB). CPU speed is 400Mhz, disk is 10GB and using less than 1/4 of space. Question is the best way to resolve the problem, by tweaking something!