I wonder if this is a problem with the radio itself.
from a school project yrs ago- I remember the 555 timing chip.
They probably use that one chip to keep time.
I wonder if its a bad chip- thats too slow- and your time goes off..
In such a case- replacing the radio (is this were the time is displayed?) would be the solution. warranty of course
http://en.wikipedia.org/wiki/555_timer_IC
On a side note....
By the way--- If youd have said your house-- I would say to check stuff---Household clocks that plug into the wall- use the 160 HZ signal to keep track of time- since its always close to 160 Hz.
I found this an issue some years ago-- when a clock I had would always display the wrong time after several days.
I eventually figured out the problem. This clock was plugged into a power strip- which also had an aquarium pump plugged in.
I think it was the motor that was somehow altering 160Hz- and changing the speed at which the clock kept time.
When I put the clock on another outlet- kept time nicely. Put it back-- time changed over a few days.
