Comment 25 for bug 1721637

(@Cleber Cassol) This is an year old issue but I had the same problem yesterday. So I did what you said, I used the dconf editor and set the dock to left and the the system settings started working again. I also had the problem where my mouse was disappearing to the right. I opened
'Settings>Devices>Displays' where I saw that the Display Mode was set to 'Join Displays' by default. I changed it 'Single Display' and now the mouse works properly. I am using ubuntu on a lenovo G580 laptop and my BIOS is inaccessible. It seems ubuntu and lenovo don't work well there have been many similar issue. Forunaely my laptop boots properly I just can't access the BIOS, many however are not so lucky...