Brightness Issues

My GMOD brightness levels seem to be abnormally high in comparison to other Source games. This especially noticeable in the main menu (seen below):

As you can see, even with the slider all the way to the right, the barely visible text is still very much visible. Compare this to HL2…

…and the barely visible text is in fact barely visible. Is this a common problem with GMOD or is something messed up on my end? Any ideas how to fix?

Thanks in advance.

EDIT: Sorry about the massive image size, not sure how to make it smaller.

Bump with a video of related issue

My specs are: Intel Core i7 Windows 7 64-bit 6GB RAM NVIDIA GeForce GTX 480 I updated my drivers recently but the problem was not fixed.