Me too - AMD dual Core X2 4600+ with nVidia card.
I can run GE just fine if I start it after a fresh reboot, where I have not run any other other "heavy" programs first. Then it seems to work fine without "crashing in the ground". But if I first run Photoshop, SketcjUp or some other progams first, and then start up GE it very quickly ends up with the nose in the ground when I try to tilt the camera. A side-effect which is also happening then is that when I double-click one of my spots in Norway I never fly all the way. It always ends up high up in the sky and far away. When GE is fresh it seems to fly straight where I point it at, to the predefined view position.
I tried setting the affinity to CPU1 only, and it seems to work OK. But then I lost all my bitmapped textures on my SketchUp models

I attached a kmz file to see if you also lose the textures.
I just installed the Dual-Core Optimizer, but after rebooting I have to run a few heavy programs first to see if GE still crashes.