vev46

When using my MS Word 2000, I have recently discovered that when I type the word "long" after I hit the space key, it adds the letter "o" and underlines the resulting word (loong) in red, indicating a spelling error. This can be corrected with the spell check feature. This occurs only when "long" is keyed in, rather than copied/pasted. I have not yet found any other words that exhibit the same phenomenon, but that is not to say no others would. I would appreciate any ideas on the cause/fix of this weird problem.