Laptop 'freezes' after about half an hour of... (by 2 users)

I think you probably have driver/software layer communication problems. In my experience, it is often driver support for either a USB device or a network card. Try unplugging everything from it and turning off network devices and see if that keeps it from freezing, and then turning devices back on one at a time and figuring out the culprit that way, and then searching for updated drivers.

It could also be a virus or malware program. Make sure you are using updated anti-virus protection and the latest patches for your operating system.

If you get really stuck, when it starts to freeze on and off, press the keys CONTROL and SHIFT and ESCAPE together to bring up the task manager and try to identify what process might be using an unusual amount of memory or processing power and stopping other processes.

Good luck...