Garry's mod problem

[Mangochutney]

After a big update the other day, I can't launch Garry's mod on Steam.
I have deleted and re-installed the game, also deleted the folder in SteamApps.
Message I'm getting is...

Unable to load c:\program files
(x86)\steamapps\xxxxxxxx\garrysmod\bin\filesystem_steam.dll

Anyone else getting this error, and can anyone help?
Thanks.

 

[Mangochutney]

Thanks for that.
Never thought to look at their website!