Hard Drives Dying

Just in the several months, I have had four hard drives go bad in three desktops and one laptop. All of the computers are plugged into surge protectors and power filters with the exception of the laptop when I am away form my desk. The desktops are normally left on all the time. The area where the computers are, are well ventilated.
I have checked the voltage with a volt meter and it is showing normal voltage but unable to determine if spikes or surges are happening.
Are there any suggestions to what I should be looking into? Any suggestions and ideas would be greatly appreciated.