I've tried changing things in skin.xml but couldn't fix that and now suddenly when I add-
<element id="Panel">
<images stretchY1="1" stretchY2="1"
default="Images\Background.png"
/>
</element>
MusicBee can't start and shows errors.
I don't know what is wrong exactly, but I do notice you have removed quite a few elements from the skin.xml
Not sure if that is directly related to your problem, but as a general rule I would start with a well-functioning skin.xml, and then edit or remove things step-by-step.
That should make it easier to spot where things go wrong.
If that doesn't work and you keep getting errors you could post the error message. That might give a clue.