After finishing game, main menu is now black screen

[Qwinn]

I just beat Portal for the first time today. Obviously things were working fine at that point. I quit the game, and now when I go back in, where the main menu screen should be, I just get a black screen. I can hear the music, and if I use the up and down arrows I can hear that it's moving through the menu options, but I can't see anything. I have tried verifying the game files (verified fine), clearing local content and reinstalling, replacing config.cfg with the config_default.cfg file, and starting under a couple of different resolutions (not sure what the default resolution is though). Multiple reboots. Nothing seems to work.

[Qwinn]

Oh, incidentally, I played through the game initially in 3D. Now, when I have 3D enabled and try to load up, the first couple of screens prior to the main menu are only displayed partially, only the top third of the Valve logo shows for example. Disabling 3D and enabling GSync instead fixes the Valve logo but still get black screen main menu.

System specs:

CPU: Intel Core i7-5930K 3.5GHz 6-Core Processor
CPU Cooler: Thermaltake Water 3.0 Ultimate 99.0 CFM
Motherboard: Asus RAMPAGE V EXTREME EATX LGA2011-3
Memory: G.Skill Ripjaws Series 32GB (4 x 8GB) DDR4-2666
Storage: Intel 750 Series 1.2TB PCI-E Solid State Drive
Storage: Sandisk Ultra II 960GB 2.5" Solid State Drive
Video: 2x Gigabyte GeForce GTX 980 Ti 6GB Video (2 way SLI) NVidia Driver 353.62
Case: Thermaltake Core V71 ATX Full Tower
Power Supply: EVGA Supernova P2 1200W 80+ Platinum
Monitor: Asus ROG SWIFT PG278Q 144Hz 27.0" running 2560x1440p in 3D or GSync.
OS: Windows 10 Pro, NVidia Driver: 353.62

[Qwinn]

Huh, refresh rate was set to 120hz, changed it to 144hz and I can see the screen again. Weird, but I'm fixed. Hope this helps someone else someday :)

[Blitzkrieg]

U beat it for the first time? awesome! I've beaten about just 16 times srry just bragging....

[Blitzkrieg]

Also get Portal 2 it better.