The Windows Explorer thumbnail extractor for *.ico files is messed-up. If it's a Mac icon and you're using a Windows, it won't have a thumbnail and you won't be able to use it as a Windows Icon. Open it with RWIE and see what happens.
saving an icon
I created an icon and saved it to my personal icon folder, but when i try to use it or view it, it comes up blank. Any ideas what I may be doing wrong?