Mod Edit: Split from http://www.bleepingcomputer.com/forums/t/544157/error-cant-initialize-plug-ins-directory-please-try-again-later/ - Hamluis.
And we probably just found the source of your problems. ;) Permissions on your Temp folder are wrong, change them to match mine, except with the last one - replace "Slavko" (this is my account name) with yours.
After that, reboot the computer and see if Dropbox starts working.
Also, make sure that in "Owner" tab is your username listed as an owner of this folder. If it's not, change it.
Same problem here unfortunately and I can't see your settings at that link. Did you take the pic down?
Edited by hamluis, 12 March 2016 - 05:28 PM.