Encore CS5 error: "file already exists", Code: "6", note: "IG button exceeds video bounds.

I've confirmed that the error is "file already exists", Code: "6", note: "IG button exceeds video bounds.  The error happens as soon as the build gets to the "building streams" stage.  I've tried it running as administrator also. 

But I've figured out the issue, though it's odd:  I turned off all the button layers in photoshop and turned them on one by one, attempting to build the project.  I discovered that are two buttons that are causing the error.  All buttons are identical but slightly different shapes.  All buttons touch the edge of the canvas.  "Exceeds video bounds" was a clue:  When I deleted the edge of these two specific buttons that touched the edge of the canvas, the error disappeared.  Then I shifted the buttons back over so that they touched the edge of the canvas again -- no error.  So I'm still not sure what actual problem was, but it had something to do with the edge of the canvas.  I did do a crop layers to canvas at some point when I built the menu in photoshop, so I know that that's not the issue, but it could be related somehow.