I'm running Knoppix 3.7 on an hp4600 series laptop and although most things work fine, I get occasional freezes (requires a power of/on to restart). The config is as follows:

hardware:
hp ze4630us (AMD 2800+/1Gbyte RAM)

disk 80Gbye with 40 GByte ext3 partion for Linux
kernel 2.6.9 (never managed to get the 2.4 kernel up with acpi)
acpi works OK -- without it, the fan ran continuously
WLAN works fine (still have to figure out how to get it to start up automatically, but when its up, it is OK)

There is no obvious pattern to the freeze; it may go a day or two, it may freeze after a few hours of use. It has never happened while idle, so it is conected with some user action. (Reminds me of early Windows problems with Athlon and video; but this was fixed eons ago, wasn't it?)

Is there anyone who can suggest a fix?