You possibly got a driver issue/congflict. If you have installed some thing recently uninstall those and see if it solves.
Also Consider running chkdsk on all partitions. Let chkdsk complete on each partition and see if that helps.
It can be helpful to use Driver Verifier. To enable Driver Verifier... start->verifier.exe->OK->Create standard settings->Next->select driver names from a list->Next->sort by Provider->select all non-Microsoft drivers->Finish, and OK your way out of the dialog.
Then, reboot and use the system as you normally would, and wait for a problem. In the event that the system does not boot completely after enabling driver verifier, boot into Safe Mode and run driver verifier, and tell it to delete the changes.
Wait for a bugcheck to occur after enabling verifier as described, and then upload the dump to your SkyDrive, and provide a link.
Consider testing memory with Windows Memory Diagnostic or memtest86. Note that memory that passes tests is not necessarily good memory - it just hasn't failed a test. Other common suggestions include ensuring drivers are up to date, as well as ensuring that you're using the latest BIOS.