I would call an electrician; or call your landlord. If what you say is true, there is a serious safety issue. if you rent, its really not your responsability (but it is your problem).
Now, let's also think diagnostically. Have you measured this on more than one outlet? Are they the same? I presume you are measuring AC volts?
I would also measure with a small draw (large impedance) across the two leads (must do this safely, well insulated). Consider maybe 100,000 ohms. This will give an idea of the actual current capability of the issue. at 100,000 ohms even a 1/4w resistor will handle the total power (about 60 mW @ 80V farmers math)
The neutral and earth ground ought to be connected.
And to confirm the above the larger slot in a polarized socket is neutral =~ ground (at the pole anyway).
