ATIKMDAG stopped responding and has recovered

It has something to do with the driver's incompatibility with Vista, and it's been happening for years. There is no real, universal fix. In fact, I personally think that 8.12 made it worse:

http://www.tomshardware.com/forum/258853-33-anyone-noti...

If you overclocked, you overclocked too far. I'd either turn down any overclock, or turn up your fan, and make sure your case has good ventilation.

My card is not overclocked. the clocks are on stock values, eaven the CPU is not overclocked

I`ve try with different driver versions..... but it is still happening  

I have a one-year old quad-core system. Quality components, very simple, very stable, good power supply, no excess heat (GPU 37 degrees C), no over-clocking, running Vista 32-bit. The motherboard is an Asus P5K-V. I do not play games. I recently upgraded to a dual-monitor system, which required more than the integrated graphics, so I got the Radeon Sapphire HD4670, another simple mid-level solution that would provide two DVI outputs at any normal resolution. (Somewhat reluctantly, remembering other ATI cards in systems and years past.) I installed the latest stable driver (8.12). Now I am experiencing _daily_ crashes with the atikmdag display driver message. This is highly frustrating. ATI support says to check hardware issues, and attempts to put the blame on any and everything else in the system. For many enthusiasts who tinker with their systems this will result in them thinking "Hmm, I must have done something wrong here." I don't buy it. In my system the only change was the ATI card, so it is the problem. Looks like the tradition of shoddy engineering, incompetent programming and poor customer service is alive and well at ATI/AMD today.

Wow.

If you had asked for help, I'd offer some. Trying a couple different drivers helps, and making sure old video drivers were uninstalled helps.

As far as shoddy engineering, I'd say the HD 4670 is one of the best pieces of mid-range engineering we've seen in awhile. Last gen's high end at about 60 watts and <$80, that's quality work.

Incompetent programming.... sounds like you've never coded anything, let alone know the problems faced by programmers.

But hey, you seem to know all the answers, so I won't offer any help.