This started to occur during November. I would be on the internet, in some cases for some time. and then the screen would freeze, and I would have to re-boot. Then it would happen again, and again. I checked that the Microsoft updates were up-to-date, cleaned out the temporary files, etc using cccleaner, and also cleaned up registry using ccleaner. Updated from IE9 to IE10, and the frequency reduced, but the system became really slow. I then switched from using IE10 to Chrome, but the freezing still happened, and after a couple of days I switched back to IE10. The freeze now happens every few days as opposed to daily - even down to once a week. The screen freeze means that I have to re-boot so I can't check if there is anything obvious causing the problem. Are there any checks I can carry out after I re-boot to identify the cause?