Sometimes Medal needs extra permissions from your computer in order to run properly. You can run Medal as admin by right-clicking the Medal.exe shortcut and choosing run as admin.
You can choose to always run as admin by doing the following:

  1. Find the Medal.exe shortcut, right-click it and select Properties
  2. On the box that pops up, click the `Compatibility` tab

  3. Click the box that says `Run this program as administrator`. Click Apply and OK.