Powerbook freezes/locks up
just got my 15" Powerbook G4 1.67 w/ hi-def screen. i'm new to Apple, so not sure what's wrong. my PB seems to be just randomly locking up. the keyboard & mouse are of no effect. i have to hold down the power button to get it to turn off, so i can reboot it. this thing is new & this is the 1st day. i love this thing & its functionality, but this freeze up thing is crazy. any advice? i had to reboot it 4 times so far in this manner! have all software updates loaded, too.