Alright, so I tried the following ;
-Rebooting, obviously
-Check integrity of Source SDK Base 2007
-novid and -windowed in launch options
-Wipe gesource completely and install it from scratch
-Uninstall/Reinstall Source SDK Base 2007
Still no luck at all... This is what I get every time I start the game ;
Source SDK Base 2007 by itself boots and plays fine, but GE:S explodes at each launch.
EDIT : I have noticed that the game always crash after a certain amount of time, If the game loads fast enough, I can get to the menu and see the options and hear the music, but it'll crash after 5 seconds or so, no matter what.