I've recently had a stubborn folder in my Trash which I haven't been able to delete for ages due to an getting the following error message. "The operation could not be completed because the item '{folder name here}' is locked."
After a little digging on the Apple site I've found this (and it's now here for my future reference too)- Open Terminal (/Applications/Utilities).
- Type this, followed by a space: sudo chflags -R nouchg
- Drag the folder you would like to unlock into the Terminal window.
- Press Return.
- Enter your password and press Return.
For further info check out http://docs.info.apple.com/article.html?artnum=106237