I would try reimaging this computer, as it does not appear to be activating properly hense it will try again after 3 days to activate it again. You can try to do a os repair to see if it will solve the activation problem, but I doubt it will. You may save more time by reimaging the system then trying to solve this problem by waiting for someone to come up with a solution.
http://windows.microsoft.com/en-IN/windows7/activate-windows-7-on-this-computer