My first guess would be that it's a heat problem, since it appears after a certain time of use. A matter of dust, dealt with by cleaning the computer = get the vacuum cleaner. Be sure to clean the income and outlets of air. And check that the fans work. The .dmp file shows ntoskrnl.exe failure, and that can practically be anything, since it's a main part of Windows, but there are no other files mentioned, meaning it shouldn't be that bad.