could you try to install Boxcryptor while running a debug log?
To start the setup in the debug mode, open the run command of Windows (Windows button + R) and type in the path to the Boxcryptor setup. Add the parameter "/log Log.txt" (e.g. "C:\Users\rrw2118\Desktop\Boxcryptor_v2.0.409.325_Setup.msi" /log Log.txt)
After running the install, you should find a logfile within the setup directory.
Please send this file to email@example.com, and just mention this thread. Thank you in advance.