Pixel Aspect Ratio problems (Photoshop CS4)

Hello,

I'm new here, but I'm using Photoshop since the Photoshop CS versions. However I'm quite unpleased to see the following since I installed Photoshop CS4 from my university (it's a legal version).

I can't seem to draw simple circle. (Yes, I pressed in the Shift button to draw perfect cirlces and squares) I get the following:

Direct Link: http://img25.imageshack.us/img25/1994/helpk.jpg

This is not a circle and my grid lines aren't even like squares they're more like rectangles. Now some details about my monitor. It is a 15,4 (if I'm correct) widescreen laptop, at the resolution of 1024 x 768. I didn't have this kind of problems with the CS3 version (which is also legal).

So I though let's check the pixel aspect ratio, however normally I set it on "square" and this problem will be fixed. Now if I set it on square I get something like that image I posted. So I tried removing the pixel aspect ratio correction, but it didn't help, because it is disabled on square.

Now I'm searching on google but nobody seems to know the solution of this problem. Please help me, because it's really hard to work if you can't view things properly.

Thank you for your time and your response, I really aprreciate it.

Nevermind, I've solved my problem by calculating my correct pixel aspect ratio.

ya, he his right if you are set your pixel aspect ratio, you can solve your problem.