Boarder, There and Marshall Law

There instead of their

Boarder instead of border

Marshall law instead of martial law

Basically those are the most frequent errors I see on discussion boards. Also I am not sure why but "there" and "boarder" irritate me way beyond anything reasonable. I am curious why. And English is not even my native language and I suck at it.

Anybody else has similar feelings about the errors I've mentioned?