Why don't you just turn the spell checker off and check your spelling the old fashioned way?
I think I am pretty good at spelling, but we are all in a hurry with our charting. If you aren't moving fast, you are wasting extra hours at the office. I can almost guarantee, that checking the old fashioned way or not, you are making errors. Run the spell checker when you are done and see... spelling errors are unprofessional in this day and age.