Hmm, I can only suggest to try turning off the OpenGL rendering mode, in case you have that enabled in Tiled’s preferences. This is known to have instability issues on Windows.
Hmm, you need to make sure to have a valid version of Qt set up first. Click that “options” link to go to the relevant settings page. Generally though, you’ll probably have to back to the Qt Maintenance Tool and install additional components, like Qt 5.5.1 for MinGW and the MinGW compiler itself.