It sounds like you're on windows based on what you stated. If you are, have you closed all of your web browsers? Have you also initiated the Task Manager (Start Menu>Run>taskmgr.exe). The Task Manager allows you to see processes that are running. It may be a bit confusing to see all of the processes but if you see anything that looks like FlashPlayer in the Image Name.... well report back and tell us what you see in the Image Names as far as Task Manager is concerned (Processes Tab)..
In addition, if you continue to have problems please download the installer and try again from the following FAQ: