See attached. I found out the issue is that the header background picture is clickable and leads back to the forum main page. The problem is that the entire image is clickable and the bar with the Facebook Symbol, Twitter Symbol, "Sign In" and "Create Account" is dynamically positioned according to the resolution of the display device. On a laptop with a resolution of 1280 x 800 and my phone at 854 x 480, the image covers up the bar and you cannot click "Sign in" on a a display with a horizontal resolution less than 900 or so and you cannot click on "Create Account" on a cell-phone sized display. In the image, I have the header image highlighted so you can see how much space it takes up and how it's bleeding into the bar mentioned above. In the screenshot, you can still sign in though it does cut into that button's space a little bit.
My recommendation would be to make the header image not clickable.