When writing in Word and copying to paste onto the web, I always suggest that an interim stop be made, NOTEPAD. Paste you content in NOTEPAD and then reselect and paste into the text area on the website.
Lots of people have tried to wrangle the output of Microsoft into submission. It isn't easy.
Pasting into NOTEPAD, correcting any typos that you see there, and then continuing on has a nearly 100% success rate at avoiding underlying wickedness.
Someone might suggest that ignoring Word completely and just typing your draft in Notepad would be easier...