Sounds like you may have something you don't want on the computer. Virus, malware, bad program, etc.
Try shutting it down and then start it up in "Safe Mode". If will give you limited access, however if it runs fine, no freezing, then you need to scan the computer for the things mentioned above, and remove or uninstall what is causing the issue.
How to enter "Safe Mode" when booting the computer.
In Windows 8 and 10...
As your computer restarts, press F8 (possibly a few times) to enter "Safe Mode"
a. Press the "F4" key to Enable "Safe Mode".
(The computer will then start in "Safe Mode" with a minimal set of drivers and services.)
b. Press the "F5" key to Enable "Safe Mode" with Networking.
( Once "Safe Mode" with Networking...