A month ago I have installed Windows 7 64 bits on my Dell laptop. It worked fine. But today I turned it on again, loged in to simple user account and windows hanged up. Before hanging up after log in you can see task bar and gadets, but the icons on desktop do not appear. Soon a pop up menu says that Windows Explorer has stoped working. The OS restarts it and windows freezes. Then you terminate the computer. If you log in to admin's account it works for a while fine, but the window used to freeze once a while. I have switched to Safe mode loged in as simple user, but experimenting with applications does not make any difference. In fact, it show the pop up menu saying that Windows Explorer stoped working. Then the OS restarts it. I was trying to run Avira Antivirus, but the ciomputers tends to freeze and yet the scan has not been completed. It has identified some sort of hidden object at that time.
What's the problem? Do I need to reinstall the OS?