Strange freeze on 2.6.21

[Konstantin Kalin <konstantin.kalin@gmail.com>]

Hello,

I'd like to ask your help with strange behavior of kernel 2.6.21-7. 
Sometimes it becomes to inoperable state and the system time stops. Also 
I couldn't ping the system that moment. But if I try to use keyboard the 
system will wake up and begin working. In other words all programs are 
continuing work normally - there are only one thing - the system time is 
slow on delay between moments when the system had stopped and I used the 
keyboard. It happens on several computers but they have similar hardware 
(AMD64 X2, ASUS M2NPV-VM).

I need an advice how I may collect information about the moment when the 
system stops. /var/log/messages doesn't contain any useful information 
near the time of stopping. There are nothing strange.

Thank you,
Kostya.