In principle, as a former MS user, I will not reboot unless really *forced* too.
Isn't linux smarter than that???
I logged in to a different user, but forgot to close the open session of synaptic
(which I had started from root konsole).
The other user got a root password prompt, and then nothing else happened.
I logged it out.
Back in my own desktop, I saw that synaptic was active
so I closed it, and went to try again.
Now the other user has the same problem as mine - I click synaptic and NOTHING happens.