Lock Cell based on Condition and Repeat till Last Row

Hey Guys

I'm trying to get this code to run :

HTML Code: 

Basically, it needs to detect whether a value in Col E is "YES/NO" if it is "NO" or blank, then the corresponding cell in Col H needs to "0" and Locked, so the only way a user can enter a value is if the cell in Col E is switched to "YES" again

This should be repeated for as many rows as there are from H17 downwards
If H17 downards happens to be blank, then the macro should exit ie do nothing

I've been running into continous loop problems and have not yet been able to solve it

Any ideas here?