Hello, kga943. I want to second what MattyB said, when is it freezing? If the computer is on its desktop and the mouse and keyboard seem to be unresponsive then it could be an issue with your operating system drivers. When I had windows 8.1 every once in a while my Keyboard, Mouse and headset would all "Disconnect" and be unresponsive until I restarted the computer. However, the fix for me was upgrading to Windows 10 Pro so it was obvious (for me) that it was an issue with the OS.
Recommended steps (If you haven't contacted dell and it's only unresponsive keyboard and mouse but computer functionality remains okay)