Hide spelling errors in document

I have a document that I update and in the Spelling Options I have the
"Hide spelling errors in this Document" UNCHECKED. However, recently
"Hide spelling errors in this Document" is CHECKED. When I unchecked
"Hide spelling errors in this Document", a dialog box comes up saying
"There are too many spelling or grammatical errors...to continue
displaying them...." I click "Check Document" and I close the
document, but when I open it, again the checkmark is there again.

How did Word put a checkmark without my permission? I am using Word
2002 and the Normal template shows the "Hide spelling errors in this
Document" unchecked.

Thanks