"The certificate couldn't be verified because a wrong system time (mine was reset to 31/12/2000). You can check by executing `date` from the terminal (is located under the utilities).
To fix the date execute: `date MMDDHHMMYY` (M=Month, D=Day, H=Hour in 24-hour notation, M=Minute and Y=last 2 digits of year).
After this you can install Mac OS..."