Everything that can be invented has been invented - US patent office 1899
You can often search in vain for that "other person or program" and you still can't delete the file. What do you do then? Reboot.
A new utility, called Unlocker, aims to resolve this annoying behaviour. Install the software then right-click on a locked file, select 'Unlocker' from the popup menu, hit 'Unlock All' and you are done. You can now rename, move or delete any file.
If Microsoft had added something like that to Vista I would be the first one to stand up and applaud.
Get the free software here. µ