My system: ubuntu 12.04 64-bit 8 GB memmory Intel Core i3 540 AMD ATI RV710 [Radeon HD 4350] - graphic driver
I have tried to figure out what is causing the freeze, but not found it. It happens typically when I browse in any browser with sites with flash content or are more graphically. It also freezes when I use virtualbox and I have had a lot of difficulty installing different distros on the virturalbox. I have manage to install after tweaking virtualbox, but it still freezes the whole system.
I have tried both to not use the proprietary graphic driver and not, both freezes.
I was running ubuntu 10.04 LTS before and everything worked fine until after I installed ubuntu 12.04 LTS. I have put more memory in between, but running memtest did not find any errors.
Regarding browsers, chrome was the worst browser, so I have uninstalled it. Opera and Firefox still crashes.
I have tried Ctrl + Alt + F1 - no response. I have tried Alt + SysRq + REISUB slowly - no response.
What happens is that the screen locks and there is no response from any equipment. Only way to get it running is to push the reset button on my computer.
It actually froze when I was using the Firefox spell checker (right mouse click) on this question.
So how can I get a stable system? How can I find what is wrong? How to fix it?