NMI running X with dual-monitor

[ivan anyukov]

Hi guys,
I'm running 7.2-STABLE on a Thinkpad T60.
When connecting a second monitor to my docking station sometimes my FreeBSD
freezes.
kgdb on the vmcore-file says "non-maskable interrupt trap"
Some details:
X.Org 1.5.3 using the radeon-Driver
I think the problem appears when moving xterms from the first to the second
monitor (or back). The mouse cursor looks _very_ strange then and after some
minutes the whole system freezes.
Does anyone know about the problem? Is it a hardware-failure for sure?
Thanks a lot!