So to just complete this thread - the advanced uninstall/reinstall didn't work - in that the terminal commands did not work. Our IT department finally got involved and we finally just did an uninstall (steps 1 - 2 of the advanced instructions for Mac), had to go into Activity Monitor to manually force quit the Dropbox.app again, did step 3, skipped step 4 and just downloaded Dropbox for Mac, installed it and it is now working. No one was sure why step 4 did not work for us, but at least I have it up and working! Thank you for all of your help.