Computer freezes after system restore?

I start college in a few days and my computer was very cluttered with unused programs and files, so I decided to reset it to factory settings to erase everything and start over. After doing this, I downloaded all the important windows updates redownloaded frequently used programs like iTunes, Skype, flux, Gyazo, and security programs such as avast and malwarebytes. Now my computer inevitably freezes after 10-30 minutes of use, no matter what program is open. I'm still able to move my mouse but I'm unable to click anything. The keyboard is still responsive, but I can't alt+tab or ctrl+alt+delete. I never had a problem before the reset, so why now? How can I fix this?
OS: windows 7 64 bit
Computer: Lenovo IdeaPad y570
HDD: 500GB
RAM: 8GB