Damn you photoshop...can anyone help?

[starrylizard]

Is anyone good with Photoshop? I was paying with it adn making a pretty picture (well ok for me) and all of a sudden it refuses to let me do anything. It keeps displaying the message "Could not use X tool because the target channel is hidden."

*frowny*

Anyone know what that means? I can't find anything that says hide/unhide channel and I have no idea what it's talking about.