Are you talking about Photoshop 13 ("CS6") or are you really referencing the decade-old Photoshop 6, or even Photoshop Elements 6?
What exact version of the OS? Macintosh or Windows? Machine specs?
Please read this FAQ for advice on how to ask your questions correctly for quicker and better answers:
Hello! Please check the color mode of your document, (Image>Mode) or that the Color panel (they are not called palettes anymore) is not set to greyscale (the contextual menu is available on the right side of the panel)
Also, it is possible to select the color mode of the document when you create a new one.