My computer is preloaded with Windows Vista and now I recently upgraded to Windows 7. However, the team does not quit after upgrading to Windows 7. Sometimes I get an error screen and sometimes the screen goes black. Many times the desktop freezes and sometimes close, it gives me the option to start Windows in Safe Mode. I donít know what to do now? Because of all these problems I have to put the switch on the computer directly off the power supply. Can anyone suggest on this topic and so that I can solve mine issue.