Sounds to me possibly if you have an "earth" problem in your house.
Different Earths around your home can produce some really strange effects on electronics.
It is not uncommon to see a swing of VAC between earths....so it is possible that can be converted in a swing of VDC between circuits in electronic devices.....
http://en.wikipedia.org/wiki/Ground_and_neutralCheck your earth against different places, e.g Meter between, your wall outlet (Earth pin) and a water tap etc. (only do this if you are sure what you are doing.)
Also there is a third ground to deal with and its the phone line its self, the phone produces another voltage swing of upto 50vac and some sensitive devices, don't like that very much and added to the swing from the AC Adapter its easy for devices to be cooked.
To be honest I haven't seen this affected for 20 years but hey you never know.....
Its still probably just bad luck and cheap components.
Shaz
