Underscore key is PMSing

Hello,

Today my underscore key has decided that it has a mind of its own and will only work randomly when I hold shift and press -.

Example of me pressing - ten different times with shift held down (should produce ten underscores):

-‑‑‑_‑‑‑___­

As you can imagine this is very frustrating. I'm starting to get very angry. I only have the one year limited warranty on this laptop and I only bought it a month ago. Any suggestions? I keep my keyboard very clean and I did pop the key off to check it just in case. So dirt or dust is obviously not the issue here, especially seeing as how the hyphens show up instead when the key is pressed and there is quite obviously nothing wrong with my shift key.