Stop trolling Rory.
It's Realible snaphsot overflow. And you get this when your client tries to load to many entities on the server at the time which makes it overflow.
This is a server-side problem which you simply cannot avoid. The only thing people could do is reduce the amount of entities on the server. So the only thing you can do if you get this yourself is keep on trying until you get in eventually.
Luckily, this is fixed in Gmod13. So once that is released, you will never have RSO ever again. (I hope.)