As Microsoft tries to make things easier; they sometimes cause problems with internal security policies. Like many companies, Windows Update has a few controls on it.
A few Windows 8 installations ran into a problem when they needed .Net 3.5. The update policies blocked the download of needed files for the Windows Features wizard to install it.
Luckily; there is a support note; that explains another method to install.
All that is needed is the DVD or an ISO of the operating system. I used an ISO. A nice new feature is the ability for a virtual drive. Simply copy the ISO, double-click it and and you have the ISO mounted.
After that start an admin level CMD and use the DISM command to install .Net 3.5.
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:<Virtual drive letter>:\sources\sxs
It will run for a couple minutes and it didn’t require a reboot.