Please be specific as to which software you are referring to?
Are you trying to install Adobe Flash Player ?
Also let me know which OS and browser are you using?
Check the task manager if you are on Windows to find 'incmail' and end the process. If you are on Mac, check Activiy Monitor for related process and close and then try to install Flash Player and check.
You can download Flash player from : http://get.adobe.com/flashplayer
In case you face any issues you can try downloading from the offline installer available at : http://helpx.adobe.com/flash-player/kb/installation-problems-flash-pla yer-windows.html#main-pars_header