A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community.
Separate names with a comma.
Update... the solution of double-clicking the process to debug really fast before the dialog locks up DOES work. Frustrating, but gets me going...
I also still have this problem. Under 4.5.4 and 4.6, the Attach dialog locks up Monodevelop and I have to Force Quit. Changing the debugger...