For the past few months, ever since Valve made an update to Half-Life 2: Deathmatch, some people have not being able to play Gmod9 online anymore. Upon connecting to any server, you get disconnected immediately or right after joining with the error "Error verifying STEAM UserID Ticket". After not being able to get on Gmod9 for the past few months myself, I started doing some digging. I realized that I got this error on my second account as well, so I started messing around with things and found a fix! This fix is for anyone with the symptoms in this thread: http://eevee.facewan.com/forums/gar...nect-error-verifying-steam-userid-ticket.html NOTE: This fix will not delete your steam games but may erase any custom options and skins you have in Steam, as well as cause you to authenticate with SteamGuard again, so make sure that you have access to the email in your account settings and know your account password! Ok, so here is how I fixed it: 1. Go to your Steam folder: Code: C:\Program Files (x86)\Steam (for 64bit Windows versions) C:\Program Files\Steam (for 32bit Windows versions) 2. Delete all files in this directory except Steam.exe and the folder steamapps. It should look like this before deleting the files: It should look like this after deleting the files: 3. Go into the folder steamapps and delete the two files sourceinit.gcf and winui.gcf 4. Go back to the Steam folder and run Steam.exe, it should begin re-downloading the Steam platform files and launch Steam after it finishes. 5. Log into Steam with your account, it may prompt you to reauthenticate your computer with SteamGuard, so go through the steps and get the code in your email, put it in and then log in to Steam. 6. Let Steam finish syncing and after it's done you may need to restart Steam to see Gmod9 if it isn't in your game list. 7. Launch Gmod9, join the servers and enjoy playing again!