change background doesnt open

whenever i right click the desktop and choose change background in mountain lion the window doesnt open. I have to click the preferences icon that appears in my dock a second time to get it to appear. This is not the behavior on the other machine I have with mountain lion. If i right click and choose change background the preferences pane for that opens up immediately.

I tried repairing disk permissions and it still happens. anyone have any advice?

You could just right click on the file that you want to be the background and choose "set desktop picture" to set it as your wallpaper.

It's also likely that the windows HAS opened ... but in a different Space than the one you're in. I've gotten bitten by that before. Try making sure you are on Space 1 before invoking the command and see if that is the culprit.