Of course, the app shouldn't be requiring you to sign in to your Dropbox account every time you open it. That's not a good user experience. Something's wrong here, but I have not encountered it on my own PC, nor have I heard of it from other customers.
After you go through the linking process the next time, can you check in the Sync Settings to see if the link actually worked? It may be that you're going through the process, but something isn't getting set when you finish it. After you link to your Dropbox account, what do you see in the app's Sync Settings?
I already linked my Dropbox account to msecure. But everytime I open mSecure, this dialog keeps poppin gup and I have to log in Dropbox and allow sync again.
Can we just do one time authorization link and be done with it?