What do you call the phenomenon where you suddenly feel that a word's spelling is wrong?
Solution 1:
As an editor, it happens to me all the time. Every time an author writes "seperate," for instance, I doubt my own knowledge that it should be "separate." I double-check the spelling of common words all the time when I'm editing. My advice is never become an editor -- it slows your reading, makes writing nearly impossible, and has few rewards.
All credit for the following goes to @TimLymington:
http://dilbert.com/search_results?terms=webster