Re: ati radeon hd 52xx/42xx no luck with fglrx
There was an update released today for graphic drivers. So lets get your drivers up to date hopefully before looking at some serious problems. Type this in terminal. "sudo apt-get install update && sudo apt-get upgrade". Then check if you can turn on both at once. If the drivers work correctly then you should be able to do this. Because this works for me and I use the same driver.
Use a GUI for Monitors. It is located in system settings. If you can't do it through the GUI please report your findings here.
Read what other people have to say. No matter how experienced you are, you don't know everything.