Compiler errors

Looks like you built a binary of your game in the Asset folder which is bad practice. Why that? Because next time you want to build your game it will try to add the existing binaries to the build while attempting to replace them.

You should always build your game outside the Asset folder. So first, close Unity. Then remove all previous build (that is: folder j_Data and executable j.exe, or j.app). Then try to build your game again in another location on your hard drive.

"Have you tried turning it on and off again?" -- that's usually what I try when I get internal compiler errors. So far I was lucky and they all went away after a healthy restart. (doesn't usually work with other compiler errors, though)

Edit: Wait, no... after this answer I retagged your post and had a look at the questions with that tag. Found this http://answers.unity3d.com/questions/39591/unity-compiler-errors.html ; sounds very much like your problem...?
Edit again: No, sorry, I should read more carefully oO that solution doesn't sound right for you... drat... sorry.. but maybe you have a look at the other threads in that tag...?

Thank you so much for your answers. it turns out the j_data folder was the cause. just deleted it, and problem solved. thanks again.

If you have McAfee, turn real timing scanning off , because McAfee real time scanning blocks the right Unity 5 files finding the right game files .