Occasionally when I move the mouse or (less often) when I'm typing, the keyboard and mouse will both freeze. They are completely unresponsive. Typing or moving the mouse does nothing. I've tried the numlock and capslock keys, but the keyboard LEDs do not change.

I'm using a PS/2 mouse and keyboard. I've tried unplugging and replugging the mouse and keyboard, but this does not fix the problem. If I plug in a USB mouse, the USB mouse will work fine. I don't have a USB keyboard to test.

To me it seems like the computer stops servicing the keyboard and mouse interrupts. Otherwise the computer seems fine since I can SSH into it. Here are some interesting things I've found:

The number of interrupts from IRQs 1 and 12 (keyboard and mouse, respectively) do not change, as reported by /proc/interrupts.

This time it froze when using the keyboard (IRQ 1).
unhandled seems to always be 0 when it's not frozen, and 1 when it is. I don't know if the timestamp matches when the keyboard froze or not, but it's usually within 10 minutes.

I've taken a multimeter to the PS/2 ports on the back of the computer. It looks like the computer is forcing the clock signal to ground on both PS/2 ports, inhibiting the mouse and keyboard from sending any data.

Any ideas on how to fix this?

Is this a momentary thing, or do you have to restart to get the devices working?
If momentary, try running the top command (or use system guard) to see if it a result of 100% CPU utilistion and which process is hogging the resources.

What's the longest you have waited for it to "thaw"?

I prefer htop, but whichever you use try sshing in & checking for hoggish processes.

Or if you're willing, set up htop in a root window in advance; then, the next time you have this problem, plug in your USB mouse & use it to goto htop. It's interactive, so you may be able to kill a rogue process w/o rebooting.

It never unfreezes. I have to restart for it to work again. No processes are hogging the processor either.

I've seen the problem occur on one other machine running a different OS (windows 98; this one runs ubuntu). Maybe it's a hardware problem or a driver problem?

Not meaning to hijack your thread, elyk, but your description fits my problem *exactly*. A cold reboot is usually necessary for me to get the mouse (and, ocasionally, keyboard) working again. I have three different Linux distros on this box and the problem appears to be the same with all of them. Since they are of different 'age', i.e. use different kernel and Xorg versions, I have ruled out Linux software as the cause.

Motherboard: http://www.gigabyte.com.tw/Products/...ProductID=1857
Mouse: Trust MI-6200
Keyboard: Dell; PRODUCT NO. ALPSCL188XX, made in Ireland, Family No.: AT101-102 (an old 'generic' type keyboard...)
KVM-switch: Aten (mouse/keyboard/video/sound for 2 PC's)

Googling for the keyboard product number, I came across this
http://www.dnull.com/bsd/oldnews/bsdnew29246.html

I have been wondering if it might be as 'simple' as the keyboard having become dirty/dusty. This because my keyborad IS dusty, and because the problem has only appeared the last month, after more than 3 years without any problems on the same hardware. The mouse is relatively new, though, only about 6 months, but the problem is only a few weeks old...

Update:
It turns out the mouse itself is the culprit. Probably the lousy thin cord. No more Trust products with my systems.