Thanks for the response!
As primary troubleshooting, I located a resource with basic troubleshooting steps that usually resolves the issue: What To Do When Your Windows 8 Computer Is Frozen
If you cannot resolve the issue with these steps, I would try the steps in this HP document next: Computer Locks Up or Freezes in Windows 8
The steps in this document can be a little more complicated, but should help. If not, the computer hardware is starting to fail, and I would contact HP phone support.
You can utilize this website to learn how to contact HP appropriately, based on your region: Contact HP Worldwide
Please let me know if you have any other questions or concerns. Thanks and have a great day!
Mario