If there is an update to parallels it shouldn't install while you are running but if it has it's likely to have tried to suspend XP while it performs them and trying that while you are working on it may have confused things (I switched from parallels to vmware so can't test it or be 100% certain)
Have you saved your document in Word recently? If so I'd kill parallels and let it restart again and continue your editing from the last place you saved it.