http://blogs.msdn.com/b/vsnetsetup/archive/2012/10/07/installation-of-net-framework-3-5-sp1-fails-due-to-an-existing-net-4-0-mscoree-dll.aspx  ISSUE DESCRIPTION: Failing installation of .net framework 3.5 sp1 with existing mscoreee.dll file version being 4.0 ENVIRONMENT: This is applicable to both 32 bit and 64 bit machines, running Windows Server2003/XP Symptom and inference : It mayen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)