My Windows 7 Dell Laptop Programs Won't Respond After 5 Minutes

So i have had it for like a month now and i got it from a We Buy Gold shop something like a pawn store so it was basically used. The laptop was working fine fast and well i downloaded games such as mmo's grand chase and i played that and it ran really well no problems. Sometimes the game would have problems and i would have to press the power button to reset it and i did maybe like 20 times i know thats bad. And now for dome reason when i log into my laptop it would take a while for the windows screen to load and then i would be logged into my laptop i would go on google chrome and use the internet watch videos after about 5-8 good minutes google chrome would load slow and then clompetely stop loading and i would exit and google chrome and re-launch it after i re-launch it it wont come up and i would try launching other programs such as control panel or any of my mmo's and they wont even appear and then when i try pressing mutiple application at a time the cpu would freeze. It was way worse before sometimes i couldn't get past the windows log in loading screen i would be loading for like and hour and I would have to power rest AGAIN. My Windows 7 Dell laptop programs won't respond after 5 minutes