I'm not sure if anyone has experienced this issue but I recently downloaded Comodo Antivirus on my mid 2010 MacBook Pro w/ Mountain Lion 10.8.2 and it made it unusable. I had Comodo installed with my previous OS version (10.6 Snow Leopard) and everything worked perfectly fine - I was always happy with it.
I didn't realize it at the time but, as soon as I downloaded Comodo, Chrome stopped working - it couldn't load any sites, then my laptop would freeze up and stop responding all together and had to be restarted. I didn't know what caused it at the time so I deleted Chrome and temporarily moved to Safari. I had almost thing happen in Safari. I could load some pages but once again my laptop would freeze up, the rainbow wheel would appear and that was it. I tried hard reset, running the hardware test nothing worked. My MacBook would freeze up a couple minutes after turning back on.
I uninstalled Comodo because it was the last application I downloaded before the issues began and everything went back to normal. I've had no issues since.