Mac OS hanging itself - need rebooting remotely

I have Mac OS 10.3.9. My machine hangs very often for no reason. I need some way that either helps me finding the cause of hang Or helps me forcibly rebooting the machine.

All Suggestions are Welcome.

Open up Activity Monitor and select "All Processes" and sort by CPU usage. Keep an eye on it periodically and hopefully you'll see what's causing the problem.

I use 10.3.9 and have no problems, so it's probably some third-party application. I know that I did use some software recently which caused the system to hang, so I stopped using it. Can't remember what it was though, but it was probably third-party (i.e. not Apple).

I had some hanging problems when I was using tiger... I did the all proccess thing to figure out what is was.. this was a couple weeks ago, and I found out that it was VNC... so if your running vnc and are no longer connected to the server some times that will use up to 90% of your proccessor and cause it to hang.