I have noticed every so often probably once or twice a week when I use usb hard drives and flash drives with the ibook which I do a lot that it locks the system up. I noticed recently that 9/10 if you just yank the drive out which i don't really wana do everything goes back to normal as before i just powered it off from the button. I have noticed it's done it once or twice with my iMac too, but I use that machine far less frequently. This some sort of known software bug or is there a fix or way to prevent it? As a part from that i haven't had any crashes, just a odd bluetooth issue that was sorted by a restart and another incident that panicked me more as suddenly the computer seemed to power down, (screen went off) so turned it off the ibook off completely at the button and worked fine after that.