correcting image distortion

My digital camera has a tendency to distort as the image nears the outside of the frame. Is there a photoshop function that can correct this? I have tried the Transform functions (skew, distort, etc), and correcting half of the image is easy by dragging the corner grips away from the center to stretch the image, but, when I go to the opposite end of each given side, the distortion returns. The problem is the grip at the midpoint on each side moves with the rest of the side when using this feature. Is there a transform feature or other command that does something similar, but the midpoint grips stay stationary, basically taking the rectangular shape of the image and making it into an hourglass or four pointed star?

By the way, how do I include an image with this thread? I am new to this site!

just post a link to the image www.your image.com as for your problem, I would say that the best solution would be either a. a new camera or b. take the image at a highres and crop it as to remove the distorted portion.

hrm... i don't exactly kno which distort you're talking about... but when it comes to making pictures bigger and i only want a certain part of it "stretched," i:
-use the marquee tool,
-select what i want stretched,
-then use the move tool to stretch it...

don't kno if that's clear instructions but ok =P

Some digicams tend to fisheye slightly because of the lens shape.

I had the same thought as Moochan based on your description. Sounds like it's your lens distorting the image. Without seeing the image, I'm not sure what approach I'd try--but another possiblity might be using the liquify tool.