My custom icons are becoming deformed when i use them

Hello everyone, this is my first time on this site
I feel very nuts, I can't figure out what is going on
I think I'm doing everything correctly, making a 48x48 image, saving as .ico
but then when i go to change my desktop icons, this happens:


there are extra pixels being added/cut off

Using windows xp...
what can I do..

attached is one of the .ico files