rotating in photoshop distorts my images

[bluewaterjon]

I shoot in RAW. I open images, and sometimes because of the way I shot them, they need to be rotated from horizontal to vertical. When I do this, the image becomes elongated. The strange thing is that when I rotate and it becomes elongated on the screen, when I look at the image size, the specs are the same. The dimensions have not changed, but clearly the way the image looks- and I have measured it too- is elongated. An image that is 7 wide by 5 high, when rotated, amazingly grows, when rotated, to 5 wide by 8 high.
Not only this, but when I create a new file- a transparent one with no content, and I rotate it from horizontal to vertical,say, at 7 x 5 72ppi, it again elongates it.
I can manually adjust the files so that when I rotate, they are rightly proprtioned, but it's a ridiculous pain and surely there must be something I am not aware of.
Can someone please tell me what is going on here?
Thanks,
Jon

 

[Buckster]

It sounds like there's something amiss with your screen's size ratio.

 

[dxqcanada]

What version of Photoshop are you using ?

 

[bluewaterjon]

Guys thanks thus far for your input.
I am using CS3. It happens on all my computers including my macbook pro.

 

[Peano]

Click File > New and make sure the bottom menu is set for square pixels.

 

[bluewaterjon]

OK! I think I solved it. Based on what Buckster said I did some more net research and found that it was simply my screen settings were off. I have now changed them to 1440 x 900 and they seem to work, at least for rotating.
Thanks very much all for taking the time to help me.
Jon