Cannot delete: It is being used by another person or program

Hello,

W2k3 sp2 File server.

When users try to move, rename,delete file (excel, .zip or else), they have the error

"Cannot delete: It is being used by another person or program ".

i used process explorer, unlocker to find what process handle is attached to the files but there is nothing attached. :(

I stop atv => no changes.

any clues ?

thx

the acls are ok.

Any