This error is caused by Microsoft Visual C++, not SolidWorks.
C++ is a prereq that automatically is installed with SW if it's not already present on your computer. You can try to uninstall Microsoft Visual C++ Redistributable and then run a repair of the SW installation afterwards. This should add a fresh installation of c++.
The install files for c++(VCRedist, VCRedist9, VCRedist10, VCRedist11) is in the folder for SW installation files in a sub-folder called "prereq", and can also be installed manually after you have uninstalled the current version, but SW repair is preferable.
SW repair is started from setup.exe in the installation folder, or from program&features in windows control panel.
I tried the things you wrote but still have the same error.
I uninstalled all the MVC++ and did a repair, same error
Then uninstalled them again with a clean install, same error
Then uninstalled them again and with SW 2016 Sp2.0, same error
I tried something I remembered from a few years ago with Windows Vista.
In the starting Icon of SolidWorks, I clicked on the Properties and in the
Compatibility Tab I selected "Run this program as an Administrator".
For a reason I still don't understand it works now
Hi Theo, good to hear that you found a solution. SolidWorks require administrator rights from the windows user account during installation in order to write information into the registry of the computer. It is a common issue that errors occure during installation with user accounts that lack proper rights to write into the registry during installation and the first startup of SW. You got the error at a later time, but now that you have run the program as admin once, it should not give you error again later. You may want to test that and verify that you now can start SW with double-click and still use it without the c++ error.