Software Errors During Windows Operation
Newly installed software, device drivers or modified registry settings may corrupt the system resulting in a stop error, either constantly or triggered under certain circumstances.
Hardware Errors During Windows Operation
When a hardware device malfunctions, being removed or newly added during a windows operation or start up, a hardware stop error may occur. This happens when the operating system detects a conflict between the hardware and device driver, or incompatible hardware and incorrect BIOS settings.
http://www.deskdecode.com/how-to-fix-blue-screen-beginning-dump-of-physical-memory-error/