Right click your taskbar and select Task Manager. In the Processes tab, look for any processes running called "Msiexec.exe or Setup.exe" If it's a startup item trying to install, Click Start > Programs > Accessories > Startup and delete any unknown applications. If nothing is listed, Click Start > Run > MSCONFIG > and select the startup tab and uncheck anything you're CERTAIN shouldn't be there. When installing Windows fresh, there are no startup items or services listed other than microsoft, but some applications on your PC may require them to be there so be careful.