Run the CCleaner, once's its all done then restart your computer. don't run defragment at the moment, it would take ages. Download CCleaner and run it, once it's completed, then restart your machine and try to run firefox. Also update firefox by clicking help tab then click on about firefox, it would show you check for updates click on that if it's version 19.0 it's up to date. Once you have run Ccleaner, reboot your machine and try it.

Load two pix at a time.