Dropbox could not be sync or connect

Hi all,
Dropbox on one of my Windows computers all of a sudden decided not to sync or even connect. Files are being uploaded to the web by my other computers, just not this one, and it's not retrieving files from the web either. Unfortunately, I have to use this computer to prepare some of my files before sending to my other computer, so this is really frustrating. Internet connection is active, btw… or I wouldn't be posting this ;-)I have unlinked the account, and uninstalled/reinstalled Dropbox twice. No better. Now it won't let me put in account information to re-link it. Any thoughts?
Thank you!
