Of course it is possible that one of these two items went bad and took the other one out (like you mentioned) and what I am about to mention may or may not be helpful but they are things to watch out for.
One, check your UPS, it should have a “Fault Red LED” on it somewhere, is it lite? It is NOT supposed to be “lite” unless it has detected a “Fault” in the AC power that is feeding it. Almost every house I have lived in had one or more outlets with this problem.
Also a bad UPS can take out electronic gear so I check my UPS every few months with software that came with the UPS to see how much voltage it is putting out and under what conditions and the quality of that voltage. I also check the battery out to see how it holds up carrying a load.
Two, Radio Shack and other electronic stores sell an AC line tester that plugs into an AC outlet. It has three lights to help you find problems. Since you have a two wire house you will need an adapter and one lug of the adapter should be attached to the center screw of the outlet's faceplate. However, if the center screw is plastic or if the outlet box is plastic and or ungrounded it will compromise the effectiveness of this device.
Three, make sure you do not clip the wider blade (so both blades of the polarized extension cord are the same size) it is important to follow the polarity of the outlet and extension cord when using a polarized outlet and extension cord. If you don’t watch out for this it can cause voltages to appear where you do not want voltage to be.
Hopefully someone with more knowledge than me on such matters will jump in since if there is something you can do to prevent this from happening again we need to try and help you find it.