If you receive an error message stating that ‘Steam is already’ running, please read the troubleshooting techniques below to resolve the issue.
First of all, please see this 'Steam is already running' topic for instructions - https://support.steampowered.com/kb_article.php?ref=8787-wyil-1543
Sometimes, if you launch the game too quickly after shutting it down, or get impatient after double-clicking the shortcut, you can get this when your system senses the game is running in two instances. If this is the case, do the following:
- Right-click on your Windows Taskbar (normally found at the bottom)
- Click on 'Task Manager'
- Go to the tab 'Processes'
- Sort alphabetically by clicking 'Image Name'
- Find mm.exe
- Click so it's selected, then click the 'End Process' button in the bottom-right hand corner
- Do this for any mm.exe instance
- Once this is done, close the Taskbar and launch the game normally - be patient when it attempts to load.