During Windows boot-up after Windows Logo screen appears, screen goes black for about 70 seconds. During this time there is no hard drive activity. It takes 2 minutes 15 seconds for desktop to appear. The same happens with a particular application which takes about 4 minutes to open during this time there is a black screen for about three minutes with no hard drive activity. Word and Excel takes about 7 seconds to open. What is happening during the black screen and what can be done about it?