Reformatting can be a huge hassle if you have a lot of important data on your drive and/or no means to backup it. You might want to try running a live Linux distribution to see how is your computer doing with a clean operating system, or memtest to determine the status of your memory.
Ubuntu: http://www.ubuntu.com
memtest USB auto-installer: http://www.memtest.org/download/4.10/memtest86+-4.10.usb.installer.zip
