and the browser appears. Press "I" again and the inspector disappears, press "B" again and the browser does NOT disappear.
 Is there a setting somewhere I missed?
 
 This has been bugging me for a while now. I'm on Sonar X3e Producer if my signature does not reflect this now.

 Oh Yeah, this is just when the browser is floating, It works as expected when docked 

I've just checked this out here, and I can't get it to not work as expected.
Do you have the inspector and browser docked ?  . . . that is, when they are closed, do you see the tabs named inspector and browser on the edge of your screen ?
 
EDIT, ah I see you've just solved it yourself.

The function descriptions in the keyboard shortcuts are different, "B" is bound to "Browser View" and "I" is bound to "Show/Hide Track Inspector". You may also notice the floating windows look slightly different. The Window controls are different. The Inspector has square edges. The Browser's are slightly curved. The Browser is dockable, the Inspector is not. Also their entries in the Views menu are different with the Inspector having a check box next to it. The hot keys "I" and "B" work to collapse and reveal the views with the views are docked at the side. So the Track Inspector and Browser are similar but do have some differences.

 Thanks for your interest, but nothing is solved. I am talking about floating browsers and inspectors. I wonder why my hotkeys I & B do not act the same. "I" toggles the window open and closed, while "B" can only open the the window, and not close it.

 Thank you, Member scook. You seem to know what you are talking about, and the gist that I glean from your post is that: That's just how it is.
 I can live with that all day long. I will however, stop busting my melon over this as of now.
 

If your browser and inspectors are floating (undocked), Alt-F4 will close them, "I" or "B" will bring them back.

Yeah, it would appear to be by design. You may also notice focus will change from the main SONAR screen to the Browser window when the Browser is already open. I would imagine it would be possible to have "B" work just like "I" using something like AutoHotkey or get used to Alt-F4 for close.

@ Member noynekker: on my rig Alt-F4 appears to close Sonar, not windows within it.
@ Member scook: None of this is an actual impediment to my workflow. The only problem is when this snags me, I spend time trying to figure it out, instead of tracking my bass or dreaming up the First Relevent Electric Guitar Riff of the Twenty-First Century.
 
This place rules

Alt-F4 should close the window with focus.