I have set various profiles on my catalyst (9.4 I think...I see no reason to use any newer version for my 4850 and my Windows XP, since I am very happy with this one), mainly to control the fan speed with keyboard shortcuts.
So, I have set 6 different profiles, where the ONLY thing that is different among them is the fan speed. These are (along with their shortcuts):
Alt+3 for 30%
Alt+4 for 40%
Alt+5 for 55%
Alt+7 for 70%
Alt+8 for 85%
Alt+0 for 100%
Now, today I put a second monitor. Everything went very smoothly, so I made them work immediately. Tried changing the profiles, I used the 30%, 40% and 70% and they worked fine.
HOWEVER, when I try to use the other three profiles, the second monitor stops working and I need to re-enable it through display properties. This makes no sense whatsoever and I would like any feedback.
Your profiles are probably saving the single monitor configuration along with the fan speed settings.
Overwright your profiles with the second display active.
Make sure to check the box to save all settings.