As the first, change the default terminal emulator, from terminator to other:
update-alternatives --config x-terminal-emulator
Synaptic can't be run in the same time as APTus, apt-get, aptitude, System Upgrade.
The first process blocks the package manager agains having access to the manager by another tool.
I can lock all processes around the package manager.
So always run only one tool which use apt.