iOS Help with xCode and Simulator

I haven't played around with iOS or xCode since probably xCode 3.2. I have 4.5.2 now (on 2 different machines) and cannot get the iphone or ipad simulator for ANY ios version (5.0, 5.1, or 6.0 - I have them all downloaded) to start after I build a project and select run. I must be doing something wrong from what I remember doing before, or must have a setting wrong or something very simple and easy to fix.

I do a new project, and don't change any code, just build and run it. The build succeeds with no issues, and then nothing happens. The simulator never runs. Under "scheme" I have a target simulator chosen (I've tried iPhone and iPad simulators for 5.0, 5.1, and 6.0 and none of them work.)

If someone could help, that would be appreciated.

Yes I downloaded and installed older versions from preferences and none worked, not even 6.0.

The simulator WOULD open on it's own if I went to developer menu and chose the simulator.

I ended up solving the problem by uninstalling xcode. First time I uninstalled on my desktop and deleted everything, then re-installed, the issue was still there but the 2nd time worked. Not sure what the issue ever was but apparently uninstalling a couple times fixed it