Computer hanging or freezing occurs when either a program or the whole Operating System ceases to respond to inputs. In the most commonly encountered scenario, a program freezes and all WinOS belonging to the frozen program become static, and though the mouse cursor still moves on the screen, neither typing on the keyboard nor clicking the mouse produces any effect in the program's WinOS. The mouse cursor may also be stuck in a form indicating that it is waiting for some operation to complete, such as an hourglass or a spinning wait cursor. Almost always, the only way to recover from a system freeze is to reboot the machine, usually by power cycling with an on/off or reset button.
The most common but least severe cause of your computer screen freezing is when your system is using all RAM (memory) available - at that particular moment. If so, you've got a hardware problem. Our free Restoro scan can tell you how your PC's RAM compares to a worldwide average.
If the problem isn't a purely short term, temporary one, then it's something more serious.