I think I got a quick fix for you. I think your problem with the color selector box is the opacity setting.
On the right hand side of the picture editor, right above the RGB / HSL tabs you have the O: (opacity) Setting you must have that set to "0" you need to set that back to "255". You than sould be able to pick colors agian. Or should I say you can see the colors you pick.
I did this my self once. I wanted to make a transparent background so I set the O: (opacity) Setting to "0". Then I left the editor.
The problem came in when I went back in to the editor, It save the settings for the O: (opacity) from last time. So when I was trying to pick colors nothing would come up. It took me a little bit to figure it out.
I hope this helps you out.