My screen suddenly went grey. I initialed a hard reboot to see if this could be auto corrected. Is this a virus?

No, it isn't a virus. Mac OS X- Gray screen appears during startup. You may need to erase the drive and reinstall OS X from scratch.

Install Yosemite or El Capitan from Scratch

Backup if possible before continuing.

1. Restart the computer. Immediately after the chime hold down the Command and Rkeys until the Apple logo appears. When the Utility Menu appears:
2. Select Disk Utility from the Utility Menu and click on Continue button.
3. When Disk Utility loads select the volume (indented entry, usually Macintosh HD) from the Device list.
4. Click on the Erase icon in Disk Utility's main window. A panel will drop down.
5. Set the Format type to Mac OS Extended (Journaled.)
6. Click on the Apply button, then wait for the Done button to activate and click on it.
7. Quit Disk Utility and return to the Utility Menu.
8. Select Reinstall OS X and click on the Continue button.

What do you mean by "runs in a high optempo"?