A laptop, or even any other PC can hang or freeze due to all or any of the following:
1. if a processor or heat sink fails to work causing the processor to overheat.
2. when there some conflicting software programs installed on your pc, eg, 2 antivirus programs, etc.
3. when a virus attacks your pc or notebook and some windows files infected or other programs you are opening.
4. when the main cooling system fails to function normally causing the motherboard to overheat.
5. when the hdd develops many bad sectors - is faulty.
6. when the hdd is almost used up and you command it to run several operations/ programs at a time.
7. if you have low memory and yet running several packages that require more memory.
8. when your processor speed is low yet you have installed a bigger/ current version of operating system.
And many others......