Computer freezes and shuts down

I would be careful if i was you because if it is a fan problem and you are starting up anyway your system can overheat and if that happens you just might be buying a new pc instead of a fan :) I use driveragent.com for all my driver needs. it searches your pc after you install it and finds any outdated or wrong drivers you might have and u can download them with a click of a button :) its a small fee but well worth it i used to have to search for hours trying to find drivers and then get a wrong 1 and continue the search

Check the microprocessor Fan for clogged fins and make sure it is running, A bad fan on the microprocessor chip will cause the unit to detect that the chip is overheating and will shut down the unit to protect the micro. As for your video error, after solving the boot problem boot up in safe mode and go to device manager and delete, do not just disable the video Card driver, Reboot the system and let windows install generic driver for video and then reinstall your video card drivers, also check the sys info screen to determine what kind of video card the system has and go to their website and check for updated drivers.