Garry's Mod crashes when loading any level.

It’s been going on since last year, but every time I load up a map in Gmod, the game crashes.
Weird thing is; it only happens on singleplayer. Multiplayer is fine.
Any tips on how to fix this?
All my addons: http://steamcommunity.com/sharedfiles/filedetails/?id=273595453
Fuckton of addons
And here’s my specs.

A “fuckton of addons” is going to cause problems, especially when Garry’s Mod updates and breaks some of them. I’d test if it works without the addons

Yeah, i have only just encountered this problem today, it only works online, when when offline it happens, i am in dire need of help for this problem.