PS/2 mouse stops working when used with keyboard

hi

I have nvidia nforce430 chipset and mouse and keyboard plugged in via PS/2.
The mouse stops working when I use it while pressing any key on the keyboard. 
ie. I press space for example and start moving the mouse, it works for 2-3 seconds
then the mouse stops responding.. moused is in "select" state so I guess the problem
is in kernel. 

/etc/rc.d/moused restart wakes it up.

The system is -current as of today on SMP. I dont know if this ever worked.
interrupts are like this:

interrupt                          total       rate
irq1: atkbd0                        4105          2
irq12: psm0                         8880          6


the system uses apic and acpi. Giant is set to adaptive (both psm and atbkd is locked by Giant).
if you needed some more information just ask

thnx for help

roman