I think I found a workaround, at least on my machine. Maybe others have found this as well. I noticed in Task Manager -> Details that when clicking "Show Curves" quadprofile.exe is launched. I will get the spinning wheel and nothing will happen. If I end the quadprofile task in Task Manager, then the curves will appear. At this point I can close and open Curves again. Only when I open a new profile will it launch quadprofile.exe in which case I have to close the task again. same thing happens if I try and save/save as the profile, I will have to kill the process and it will continue on.
John M