This is a known issue which can afflict v2014 M0 PC users.
It can happen with any plugin that trying to access the latest Ruby2 functions - IF you start SketchUp by opening a SKP which is on a drive other than where the SketchUp.exe file is located [usually C:].
To see this open SketchUp as an application ans then open the SKP = NO error.
What happens is that SketchUp mis-makes the $: as it starts, and looks for the Ruby2 files on the SKP's drive NOT the .exe's drive, it can't find them, and there's the error message...
Now for the good news... ☀
A temporary fix named !_fix_ruby_startup2-1-2.rb was developed, this went into the Tools folder and as it loaded it rewrote the $: properly. You could get it and its instructions by Searching on SCF...
BUT v2014 M1 was released a few weeks ago and that no longer displays this problem 😄
See http://www.sketchup.com/download/all
So I recommend you update to the appropriate PC version from there...