No GUI. Almost everything about my game is default. The only things customized are my M3 skins and a gif spray, both of which have worked without incident for months.
Things have gotten worse. I updated my video card driver and now when I run play-css.exe, my computer reboots itself!
I guess I'll try to just reinstall.

Well I deleted my entire CSS folder, reinstalled. Running the exe made my PC reboot. I downloaded and installed a slightly older video driver; older than most up-to-date, but newer than what I had yesterday. It worked, barely. Took a while for main screen to load. In game, pressing TAB to look at the scoreboard made my game freeze for about 15 seconds, thought it would crash and restart again but then it settled and worked alright. I think maybe the cause of the scoreboard crash had to do with those little images everyone has next to their name on the scoreboard... those are new aren't they?