Thank you for your help! Yes, the remote folder had changed. I don't know how! But this is what I discovered, for those who may be interested:
The remote folder that Dreamweaver has always defaulted to has been /www. (We have 3 websites, incidentally, that I maintaiin). Now, all the website files have been residing in the /www remote folder (at least for the other two non-problematic sites). Somehow, the website files for the problem site moved to the "webstats" folder. I hope I'm making sense!
In any case, thank you again. Much appreciated.