I was using version 5.1, but that doesn't explain the osx crashes.
The screen just freezes, i.e. can't move pointer. Sometimes just moving pointer over the dock can cause a crash. Printing to HP deskjet 940c from IE can crash the mac.
I'm gonna use OS9.2 for a while to make sure it's not a hardware problem.
How much RAM do you have? Mac OS X sucks up RAM like there's no tomorrow. 64 is unnacceptible for OS X. On an iBook with 64, OS X slowed to a crawl. You'll probably want at least 128 for it to run smoothly.