Gmod refuses to launch?

Hello Facepunch!
I was launching Garry’s Mod last night and experienced this odd issue where my screen would be completely blank (white) and I’d just given up for the night.
I woke up this morning and attempted to launch Gmod, however, it’s now stuck on the “Adding Game Systems” stage at the initial loading screen. I’ve attempted to reinstall Gmod 5 times now, aswell as verify the files a handful more times.
Any help will be appreciated!