I had this problem and none of the advice here fixed it. I had uninstalled onboard, one of the screen keyboard programs. I finally got synaptic working by re-installing onboard and then disabling "Screen Keyboard" in System Settings->Universal Access->Typing->Typing Assistant. Weird.
I had this problem and none of the advice here fixed it. I had uninstalled onboard, one of the screen keyboard programs. I finally got synaptic working by re-installing onboard and then disabling "Screen Keyboard" in System Settings->Universal Access- >Typing- >Typing Assistant. Weird.