more than 5v on power pin?

Hello, I am an Arduino newbie, so maybe this is a stupid question.
I tested with a multimeter the voltage of my Arduino Diecimila board, connecting the 5v and gnd pins.
The result was of about 7.93v.

Then I tested 3.3v pin, and it was 5.36v

Then I tested pin 13 and gnd, and it was 7.87v.

The board was powered by USB.
Is this possible? What am I doing wrong?
Do I have to throw my multimeter?

Thank you for your help!

It does sound like your multimeter is faulty. Measure a fresh alkaline (not NiCad) 1.5 volt battery. if it reads over 1.7 volts your multimeter is faulty.

If the arduino was really getting over 7.9 volts on the 5v line it would probably be toast!

...it was the multimeter... -__-"
Thank you for the help!