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Installation problem

I am having trouble installing it. Studio2015-SR3.
It prompts: .NET Framework 3.5 (includes.NET 2.0 and 3.0) but when I click on Install this feature rather than skip this installation, it fails to install. It says it’s installed but then Error 1722. « There is s problem with this Windows Installer package. A program run as part of the setup did not finish as expected. Contact your support personnel or package vendor. » It seems to stick at Writing system registry values.
Package Microsoft Web Services Enhancements 2.0 SP3 could not be installed. Fatal error during installation. Error number 1603.
Many thanks in advance for your help.