"Please close Safari first" when Safari IS closed

I am running Mac OS 10.7.5, Safari 6.0.2, and trying to install the latest version of Flash 11 (as of Feb 8.) Half-way through the installation I get the warning to "Please close Safari to continue." I close Safari, try installing again, and get the same message to close Safari before continuing...but Safari IS closed.

I even try restarting the computer and installing Flash immediately...without so much as touching Safari. The installer still asks me to close it first. I open up the Force Quit window and only "Install Adobe Flash Player" is open.

Please help!