Hello,
here is what I found on
http://programminggems.wordpress.com/2008/12/16/mac-10-5-6/
"1. Click on the magnifying glass in the top right (Spotlight) of the menu bar.
2. In the text entry field type “Terminal” (in all these steps, type what is in the quotes, but not the quote characters themselves) and press Return.
3. In the new window that opens, type “cd /Volumes” and press Return [note the space in the command].
4. Type “ls -al” [the "l" is a lowercase "L"], press Return, and note the name of your backup volume.
5. Type “cd ” (no Return yet), type the first few letters of your backup volume name, and press the Tab key, then press Return.
6. Type “ls -alF” and press Return and note the file with a name that matches the error message.
7. Type “sudo rm ” (no Return yet), type the first few letters of the file name that is reported in the error and press Tab to get the full name on the command line, and then press Return. (Alternatively, you can change ownership as described in my comment #3.)
8. When asked for your password, enter it and press Return.
9. Type “ls -alF” and press Return and note that the file is gone.
10. Type “exit” and press Return to close Terminal (then use the menu to Quit).
11. Retry the Time Machine configuration."
It works fine for me, thanks Mr Foster!