hkBattousai

Now it works. Many thanks for you help.

Oh, I was looking to a wrong place. I'm sorry. I found "Turn Windows features on and off". It looks as below: What do I do here now?

There is no such item in the list. The relevant ones in the list are: Microsoft .NET Framework 4 Client Profile Microsoft .NET Framework 4 Extended Microsoft .NET Framework 4 Multi-Targeting Pac There is no item related to .NET version 3.5.

Tried to install the version: 3.5.10 Operating System: Windows 7 Ultimate x64 SP1 (up-to-date) What does this error message mean? What should I do?