[lubuntu] Aspect ratio 'wrong' after crash during upgrade

Hello,

when prompted by the Software Updater, I decided to upgrade my Lubuntu desktop PC to the new version 16. The upgrade had reached the point of installing the packages, but during that step there was a power cut! After the power came back on I checked later and found the PC would not boot!

I did some Googling and found out about a concept of 'chroot recovery' using a Live CD. It was all very new to a dummy like me, but I was able to boot off an Ubuntu USB drive and run the commands specified such that I could eventually run the key command...

sudo dpkg --configure -a

...which apparently fixes partially-installed packages.

The PC was at least then able to boot and let me log into Lubuntu, albeit with the new aspect ratio problems I will get to shortly. I ran the Software Updater which suggested proceeding with a Partial Upgrade. Eventually the Software Updater finished and as far as it's conceed, this is an up-to-date instance of Lubuntu 16.04.

However, the aspect ratio problem remains. Basically: the screen displays content as 'too wide' and 'squashed from top to bottom'. This is despite using the same 1024x768 resolution on the same monitor, all of which looked perfectly good on the previous version of Lubuntu.

I have attached some screen shots to illustrate the problem. In particular, see how circles are displayed as ovals!

It seemed highly likely that the problem was a knock-on effect of the power cut/crash during upgrade and/or me doing an imperfect recovery from it. I next tried ruing the upgrade on my Lubuntu Netbook. Free of power cuts, the upgrade completed with the aspect ratio remaining 'correct' and everything looking nice and easy to read.

Does anyone know how the aspect ratio on the desktop PC can be 'fixed'?

Display Settings.jpgMozilla Firefox.jpgLibreOffice Writer.jpgGoogle Images search results for 'circle'.jpg