MacPro or MacBook Pro?
What model year is it? A tower or the new black round one?
OK is there more than one drive in the Machine?
OK I suggest you do this:
1. Shut down the computer. 2. Unplug the computer's power cord. 3. Wait fifteen seconds. 4. Attach the computer's power cord. 5. Wait five seconds, then press the power button to turn on the computer. 6. Press and hold the Command-Option-P-R keys before the gray screen appears. 7. Hold the keys down until the computer restarts. 8. Release the keys and immediately hold Command - R to boot to Recovery HD. Erase the hard drive again but this time choose Options and move it one notch to the right to zero out data then reinstall.
OK if there were no problems erasing the drive you have some other hardware problem. Hard to diagnose that. Try different keyboard and mouse or the hardware test:
OK let me know