When you freeze up , Unplug the computer , literally from the plug on the wall. The computer will treat it like a power failure. When you restart it everything will work again.
Restarting your computer once in a while also tends to clear out a lot of cached crap. every time things slow down, restart.
Sites with lots of pop and snazz and sizzle often cause the most problems. They get ad-ons grinding away until things freeze up. Avoid the junk on the internet , and you avoid a lot of problems. try telling that to a teenager
Firefox browser with ad block solved most of my problems.. I still find a restart is needed every couple of days.
Some sites with embedded youtube videos have "usage counters" that grind away eating memory if they do not close themselves off properly.
Sometimes leaving the computer disabled for a few days helps the teenager realize they should have listened to dad when he said to stay off the crap sites
Good luck and restart often.