YES! I have the exact problem. It happened in Word 2000 so I upgraded to 2007 thinking it was a compatibility problem with Vista, but it continued. Do you have a weird problem with the font box in Wordpad, too?
Anyway, I've spent hours researching and even spent some money calling a help line. No luck. If you have figured it out let me know.
I have a new Compaq with Vista Home. I've scanned for viruses and malware but came up clean. So it must be a software glitch.