Only a single instance of this application can run message is displayed when i try to install Adobe Flash player on Mac 10.7.4.
I tired even to check if already previous version of Abobe is installed by going to follwing link
Flash player information area shows blank area (Not blank box)
Download the offline installer here: http://fpdownload.macromedia.com/get/flashplayer/current/licensing/mac /install_flash_player_11_osx.dmg
If it won't download directly, right click and "Save as"
Go to: Mac HD/Library/Internet Plugins
Trash the Flash Player.plugin file from there
Go to: Mac HD/Library/Application Support/Adobe
Trash the Flash Player folder (the whole folder)
Empty the trash
Mount the DMG and run the installer.
BEFORE opening any Flash content in Safari, open Safari>Preferences, and check the Security tab to make sure "Allow all other plugins" is checked.