I really dislike having to do these workarounds. However, I just spent about 20 minutes to 'educate' the spell checker. I went to a medical dictionary site, copied all the words to the clipboard, then pasted them into a sample letter. I clicked preview, then held down the return key over the add button. Now I have about 2000 words in my userdic file!
I changed the Options to ignore mixed case words, but this software is terrible. It does NOT remember this change in the options, and goes back by the next spell check!