Cannot Install Flash, "Close Firefox"

[faelwknfrewkln]

I've tried several times to install Flash Player 11, and every time I do it tells me to close Mozilla Firefox. Of course, I'd already closed it. I hit retry, and once again it told me to close Firefox. Firefox was most definitely closed. I even opened up the Task Manager to make sure.

I'm on Windows 7 64 bit, Firefox 3.6.23.

[pwillener]

Did you check the Processes tab in Task Manager?