Yousician might not start properly if you are running Windows 7 or Windows 8 and have not installed the latest OS updates. To fix the issue, you may either install the latest updates from Windows Update, or alternatively try to solve the issue by installing the Microsoft C++ Redistributable package. Once you complete the updates or installation, you should be able to run Yousician without errors.
Please note that the C++ Redistributable installer may fail on an error. In this case, please try to run Yousician again - the installation might have succeeded well enough to fix the issue. However, if this still didn’t help, please install the latest updates to Windows.