I second what Tom says about holding down the "option" key while emptying the trash. That's the only way I've been able to do it without unlocking each individual file.
Kholi,
Where you logged in in the same as the same user that copied the files over? since the files are locked and you can't unlock them then there are two possibilities that spring to my mind:
A. You don't have permission to unlock the files because they where created with a different user account.
or
B. The permissions for the file have become corrupt/messed up. This is an easy fix, you can use Disc Utility in your applications/utility folder to repair/verify any drive that is not your system drive. If you have your files on your system drive then simply boot up your original OSX Disc. (I think you hold down C as it boots up) then use Disc Utility to verify/repair your drive.
I hade some poblems with this for time to time. As said before, it seams to work less good if you have open any finder window and maby aplication windows. I think its the option key shortcut that gets confused. Aslo try reboot one time if nothing helps. In worst scenario you can go throw all the files and uncheck write protected. Good luck!
I use this process often as the option + empty trash doesnt work for me either:
taken from apple support
Advanced tip about deleting locked files
If there are several locked files in the Trash, you can unlock them all at the same time at the command line. Follow these steps:
Open Terminal. It's located in /Applications/Utilities.
Type: chflags -R nouchg Note: Type one space (not pictured) after nouchg in the line above, so that it ends in "nouchg ". Do not press Return yet.
Double-click the Trash icon in the Dock to reveal the contents of the Trash. If necessary, arrange the Finder window so that a portion of the Terminal window is still visible.
Press the Command-A key combination to select all files in the Trash.
Drag the files from the Trash to the Terminal window. Note: This automatically enters the pathname for each file. This eliminates the need to individually empty multiple Trash directories, particularly when multiple disks or volumes are present.
Press Return. No special text message will be shown indicating that the command was successful.