If both the Zip and the 7-Zip version fail to extract, go to 7-Zip and download the latest version.
If your mouse cursor is stuck in the top left of the screen simply ALT-TAB out and back into the game.
On some computers with Intel HD Graphics you might get a black screen when trying to start TO. This might depend on the model number and graphics driver used. It could help searching for a updated driver on Intel's website or your motherboard manufacturer. A work around is pressing F12 on startup to minimize TO, then you can make it full screen again and play the game. This has to be done every time on startup or set StartupFullscreen to False in "TacticalOps.ini"
File Mismatch errors only happen when you install Custom Files manually into the game folder. When files are downloaded from a game server into the Cache folder this will not happen. So do not install custom files on a install that you also want to play online with. In the case you encounter a File Missmatch error when joining a server you can try to clean or delete the Cache folder, but most likely you will have to reinstall the game if you have not made a backup folder.
Install the ESESetup.exe for the ESE Account Manager. Make sure you have registered and obtained a ESE Keyfile and place it into your TO v3.5 System folder. Configure your TO v3.5 TacticalOps.exe installation folder in ESE. Then install the ESE Client Files and the ESE Renderers and configure them from inside the ESE Account Manager. After all these steps you should be able to join ESE Servers.
Also make sure to browse to the "System/TacticalOps.exe" file and not the Tactical Ops Quick Join.exe file when using the TO v3.4 + v3.5 fixed pack.
When using custom files its always advised to make a separate installation for offline or lan use only.
.int and .u files -> TO-Version/System
.unr files -> TO-Version/Maps
.utx files -> TO-Version/Textures
.uax files -> TO-Version/Sounds
.umx files-> TO-Version/Music
Sometimes when you just joined a server you might get kicked or the game can simply crash between map loads. Simply restart the game and rejoin the server.
If you have played on a TO3.4 ACE server, make sure to restart the game or wont be able to join servers without ACE afterwards. If you get kicked on TO3.5 servers make sure ESE is activated and configured properly.
If your Internet Connection is slow, or unstable set the connection speed lower in the settings menu. Options -> Preferences -> Network -> and change Internet Connection from LAN to Cable, xDSL or lower if the Netspeed Error still appears. (This might also be needed if you play on high ping servers)
You can always send en email to email@example.com or post a comment on any of videos on the Tactical Ops Channel at YouTube.