My slackware 13.37 OS hangs after about 10 min. when the network cable is plugged in.
 

How can I find out what causes my Slackware 13.37 OS to "hang" after about 10 minutes or so? When this happens, the mouse cursor moves around the screen but the mouse buttons and the keyboard have no effect. To work around it I hold the power switch (on/off button) down until the computer turns off. Then I turn the computer back on. When the network cable is unplugged, the problem seems to go away, that is, I can work for several hours without the computer "hanging".

I looked at /var/log/messages and syslog but I cannot make sense of them. I think I can see where I re-cycled the power ("general protection") but I see no clue indicating a malfunction or its cause.

Which log file should I study? Where are the logs for network connections? Can you give me any keywords that I should look for in the logs that will provide evidence as to the cause of this problem?

I should mention that while researching this question I have been trouble-free for about 90 minutes.

My first thought is that you've got a faulty ethernet card, but try this first. When your cable is unplugged, open Konsole and use (as user, not root). You'll get a lot of information, what you're looking for is the two lines near the top that say Mem and Swap. There will be a segment on each of those lines that says "[somenumber]k free." This is saying how much memory and swap space you have free.

Keep an eye on that and plug in the network cable, and see if the number drops to zero when it starts hanging.
And right above Mem is a line that starts with CPU:, followed by a bunch of percentage numbers. Do any of those hit 95-100%?

Also
While your cable is plugged in but before the computer hangs, are you able to browse the web like normal?
You said that without it being plugged in, you can work for several hours without it hanging. Does this mean that it does hang after a while anyway, but starts earlier with the network cable plugged in?

Excellent post. Many thanks. I have to man this "top" program and get back to you.

Check your IRQs as well if your motherboard supports IRQ manipulation. Check and make sure the mouse and network/PCI IRQs aren't on the same channel.