Ubuntu :: Highlight Then Delete ; Misses First Letter In A Word / Resolve This?

When I highlight a word then delete it, the word is erased as expected. But when I highlight a word and begin typing a word to replace it (instead of deleting or hitting backspace), the first letter of the unwanted word does not erase... so I am required to watch my text very closely when editing.

For example: I'll type the word "fungus" and then highlight it and type the replacement word "mold" and when I look at the text, the word is "fmold". Am I the only one with this odd situation?