I ran across this problem this morning and need help fixing it.
I have documents stored in folders on my system and have quick shortcuts to them sitting on my desktop. This way if/when I get delete-happy with my desktop icons, I don't accidentally delete important documents/folders.
I ran across a great way to access them earlier this month that I began using. I assigned F10 to a shortcut (Word document) on my desktop. I recently deleted that shortcut as I finished using that document. Now when I try to assign F10 to another document, it won't work.
I'm assigning shortcut keys using the Properties dialog of the shortcut on the desktop. I love this option as I can be working on a document and hit F9 and it brings up windows calculator immediately. All without having to get a different keyboard than the default Dell keyboard.
Windows XP Pro SP2