Re-seat components -especially RAM.
Definitely take the memory stick(s) out and put them back in again.
Google how to clean the contacts - that's worth a shot.
Also, if it has 2 memory sticks, try removing one and see if it runs without freezing. If it freezes swap the sticks and try the second one.
If it doesn't have much memory though, it's not going to run well with only half installed.
Also USB slots - pull it all out when it freezes or try using a couple of differnt ones. A 'micro' short on a usb slot can do funny things.
Power supply - any chance it is a micro outage.e Had one job where a ups fixed the hanging issues. - although a laptop has a battery fail over os likely not that on a laptop.
Run a hardware tester over night - every night for a week. Testing a pc when you arent using it might show it never dies at night / alone, but the vibration of typing, mouse etc might cause issues.