Display Driver Nvlddmkm Display Driver Nvlddmkm?

Display Driver nvlddmkm? - display driver nvlddmkm

Hey I keep getting the following message:
"Display Driver nvlddmkm not responding and has successfully recovered"
This happens immediately after my PC hangs for about 5-10secs and sometimes pass through the screen for a further 5 10secs, I am currently using Windows Vista.