I use Steam to play Spiral Knights. But one day, I tried to open the game and Steam told me "The client is already running" when it wasn't even open. I've tried restarting my computer, logging in and out of Steam, and deleting Java from my Task Manager. Although each and every time it said the same thing.
This may help, or may not. Each time I try closing Java and then opening Spiral Knights, a few seconds after I click on the shortcut, my screen goes black for a few seconds and comes back. This probably has something to do with the problem.
Also, my computer is an HP Compaq 6000 Pro Microtower. It uses Windows 7 Home Premium. My other Steam games work perfectly, too. It's just Spiral Knights with this problem. Hope you have an answer to help me with this. Thank you.
The solution should just be killing the java.exe process in task manager.
You may not be giving it enough time to open up or a recent update caused some incompatibility with the client.
Did you recently update windows or your video card driver?
Have you tried disabling the steam overlay? (This has cause problems for other players.)