Most of the time I try to install flashplayer, it downloads up to 50% and asks me to close the Internet. When the internet is up, I close it and it still says the same thing. There are other times when I have nothing up and it still asks me to close the internet. I have opened the start task manager, which says only the flashplayer installer is open/a task.
Can you navigate yourself to Task Manager > Processes. Check if there are any processes like IE.exe, Chrome.exe, Firefox,exe. If so, end the processes. Sometimes even if an application/internet browser is closed, the proccesses are still not ended.