I have an old Toshiba Satellite L355-S7905 that was handed down to me back in 2009. It gave me some problems beforehand (needed a new OS twice since I got it) but over the past year it's been fine. Suddenly, out of the blue, the OS crashed on me a few days ago. The crash was pretty bad and the OS wouldn't boot anymore. So, I did what any logical person would do; I reformatted my HDD (to ensure no viruses or spyware remained) and attempted to reinstall Win7 Ultimate. After the install, I manually updated all my drivers, and went underway resituating my programs. All was well with the universe, and then it happened. My system froze. One reboot later and it started freezing any time I tried to launch Firefox. Shortly after that, it started freezing whenever I tried launching any program at all. It even froze when I launched the Command Prompt. I've tried everything I can think of, but nothing seems to solve the problem of the CPU spiking then the system locking up. I've tried virus scans, registry cleaner, disk defragenation, and disk clean up. Nothing's worked so far. Any idea what could be causing my system to crash repeatedly? And any idea how to fix it without spending any money?