I will be glad to help you with the issue you have with the computer. I understand the frustration when things don't work the way it should.
mscorsvw.exe is precompiling .NET assemblies in the background. Once it's done, it will go away. Typically, after you install the .NET Redist, it will be done with the high priority assemblies in 5 to 10 minutes and then will wait until your computer is idle to process the low priority assemblies. Once it does that it will shutdown and you won't see mscorsvw.exe.
I suggest yo to remove .net framework completely from the computer using .netframework removal tool and install the latest version of .Net framework on the computer.
microsoft.com/en-us/download/details.aspx?id=5942
Once .Net is completely removed from the computer, please install the latest version of .Net framework from the below link:
microsoft.com/en-us/download/details.aspx?id=30653
