Okay guys, so I got a fix (more like a workaround) for the invisible menu bug, finally!
I just ran it in RyonaniXP. Yup. That's it. :o
So I figured the people that have this bug probably have something in their PC settings messed up, but since RyonaniXP has all settings already pre-made, it just works!
Here's a link to it if you haven't read about it already. :)
Also, I just now noticed what those Skillballs are for! This makes the game so incredibly easy, you can beat the KungFu-Orc at like, level 7 or even earlier if you don't suck?
And so people with the same problem can find this, I should probably add some tags to make searches easier (hope this isn't against the rules, I'll edit to remove this if it is):
invisible menu bug, hidden menu, menu behind game, can't see menu, menu won't show, fix, help