This does not impair my ability to play but is a little annoying. I run the application from the website (http://www.spiralknights.com/play.xhtml) and before the game opens up an empty console window opens up with the title c:\PROGRA~1\Java\jre7\bin\java.exe. It stays open the whole time. If I try to close it it closes the game window.
I recently updated java. When I went to the website to verify the installation it said I had a few older versions so i removed those.
I have reinstalled the newest version once already. I will do it again.