i have windows 7 Enterprise x64 installed on my laptop. When i am trying to upgrade to windows 8.1 x64 enterprise, by running setup.exe from /source/setup.exe present in the iso obtained from MSDN. This is what happens. 1. Setup launches shows copying temporary files 2. Setup is starting 3. Suddenly the setup disappear without any error message. Anyone can tell me the reason for such behaviour and the wayout
A CD/DVD/ISO is read-only, setup.exe can't just disappear. What you describe is impossible unless you use packet writing. Otherwise there are language issues here and you should re-word your post.
Look around in the event viewer first. Try to find related error messages/codes. Crashes are usually logged.