Do other applications do that as well? I have several keyboards, and on one
of them, the spacebar is notorious for overdoing it in the space department
("Space? You want space? I'll give you space!" it seems to be saying.)
If it's only doing it in Word, I can't imagine why, unless your typing
habits are different in Word. Do you have a different keyboard you can try?
By the way... when using proportional fonts, the convention is to use only
one space after a sentence-ending punctuation. Like many others in my
generation, I took typing in the 1960s in high school, and was brow-beaten
by Miss Hall (my business typing teacher) into using two spaces between
sentences. When I began writing professionally in the 1980s, my editors
quickly brow-beat me into using just one space. It took a while, but it
comes naturally now. In addition to making life easier for typesetters, it
saves paper (in the longer run) and disk storage space, too! In your case,
it would mean fewer extra spaces to delete when your keyboard messes up.