Hi, I have a iBook G4, 1.33 1.5Mb ram with 10.4.11. I have an issue that after awhile (1-2 hours) the computer slows down and I sometimes get a message saying that my available memory is low and should quit applications. When I start up I have about 10 Gb. When I don't get that message, I usually have to force quit the computer with the power button. It's seems like something is running in the background, but when I check the Force Quit Application screen - nothing unusual shows. The hard drive is new and upgraded to a 160Gb (from a 40Gb) about 4 months ago. Any suggestions? Thanks!