The probable cause for that may have been a corruption with your OS's files. The next possible solution would be to wait it out until the numbers shifted and/or the HDD activity LED exhibited flickering i.e it was performing a task. Failing that you could perform a hard reset/reboot/power off in which you have the power button depressed.
If you can get into Safe Mode, try
sfc / scannow and see if it resolves the issue.
Since you were opting for a factory reset I think the best course of action would be to perform a
clean install provided all your critical data is backed up on an external drive.
Might I ask why you chose to reset the machine? Was there an issue you couldn't solve? Please pass on your full...