flipping layers

I am trying to horizontally flip one of the three layers in a current project in photoshop CS.

I select the layer in the layers pallette, got to edit, but the 'transform' option displays as 'transform path' and is greyed out and cannot be used...

I have tried everything I can think of, right down to uninstalling/reinstalling photoshop without success...

This is probably something REALLY simple, but I'm stuck...

Can anybody help?

Thanks!

Seb

Well the first thing I can think of is that you have:
Image -> mode -> indexed colors.
Try changing it to RGB colors and it might work.

Make sure you're not using any of the tools that use paths like the shape or pen tool. Try selecting another tool, i.e. the Marquee tool, and then try it. When using the Pen tool, the Transform option switches over into Tranform Paths.