Two ideas... The first is to use Disk Utilities and run a fix permissions operation. Sometimes that will clear this sort of thing up.
If not, then the second idea is to use the Unix underpinnings of OS X to force the deleting of the file, but let's cross that bridge if the fix permissions operation doesn't resolve it.
I have a file in the drop box of my laptop running OSX 10.5.8 I have copied it to the appropriate folder (Music) but it will not permit me to delete it from the drop box folder.
When I try to send it to the trash, it says it is locked. When I go to Get Info, it shows it locked but that area is grayed out. Even when I open the padlock with the password, it stays gray.
This isn't a major problem, but I would like to get rid of this file because it's annoying when I can't get a computer do do what I tell it. Every time I see it, it reminds me that the computer has gotten the best of me.
Thanks for any ideas.