After updating WordPress to the new 2.7 version, I discovered that aligning images left or right disorted them so that they stretched out too much horizontally, making all the pictures in my posts look fat.
I am using the theme Minyx 2.0 LITE. Users of other themes have reported similar problems after an update. My guess is this happens when theme makers don't update older themes for new versions of WordPress.
The solution. When you tell an image to align left or right in WordPress, it adds the class "alignleft" or "alignright" to the image. What I found in my theme is that these simply weren't defined in the stylesheet. Instead, there were two classes called floatL and floatR. So when you align an image, go back and change the classes to floatL or floatR. This will get your images to align and stay the original size.
You could probably code the change into the file, but I rarely left or right align images so I'm not going to bother with it. I thought I would post this because I searched all over for a solution and couldn't find anything. Hopefully the next person with this problem will stumble upon this post after doing a search.