Folder window refuses to not appear at startup.

Every time that I start up my iMac running OS 10.7, a window from a folder within the package of a program (Steam, if you must know), opens on the desktop. This happens whether or not "Reopen Windows" is selected at shut down from the previous session. No matter what I do, the folder keeps appearing when the computer starts up and logs me in. Now a huge deal, except that it drives me crazy having to close it every single time that I turn on the computer. Any ideas as to why this is happening and how I can remedy it?