I have installed VS 2015 RTM (nothing else) and I\'m unable to debug any solution, not matter if it\'s an existing one or a brand new one (created with VS 2015 and compiled
I had a very similar issue recently, related to debugging settings.
Firstly have you tried resetting all your settings? I think it may be related to that as you say it is project independent and you've deleted all application data.
Tools-> Import and Export Settings Wizard -> Reset all settings
Don't worry, it gives you the option to save current settings.
Secondly if this fails, I would suggest looking at the event log.
Entering break mode would suggest that the DE (debug engine) is sending a synchronised stop event to visual studio like IDebugExceptionEvent2. I would take a look at the event log for exceptions like failures in loading referenced assemblies (like .NET runtimes, etc) or environment access restrictions.
Something is telling the debugger to stop your running application, its just a case of finding it.