download and run bootable memory diagnostic. maybe something with Memtest86+
Check your temps. High temps can make systems unstable. I like hwmonitor by cpuid (free, google it)
If you are overclocking back off the overclock.
Reload video drivers (seriously -- for example: http://www.sevenforums.com/crashes-debugging/195182-bsod-kernel-data-page-error.html)
Run the hard disk diagnostic for your disk. Use device manager to find out who made your disk then download and run the disk manufacturers 'smart' diagnostic.