I have never had this problems until I began to use Xcode 4.2. I’m getting the following error trying to upload my app:
Unable to verify icon dimensions, no icon found. Your minimum os
version is below 3.2, so you must define CFBundleIconFile or provide a
default Icon.png that is 57×57
I have an “Icon.png” image and is 57×57. I tried add it and remove it from info.plist. No success. I don’t know what to do.

Here is my info.plist file

Info.plist edited again

SOLUTION
Thanks for your comments. The problem was that I was not following the right steps to prepare the app for submission in Xcode 4. It’s very different to Xcode 3.2. If you follow the steps of this guide you will not have the issues I had.
To avoid more replies, I post the solution (solved myself)