I read a message like this in Abakt's log when performing a Zip Action:

Tf_Action::ZipBuilderMessage: ErrCode=0x21 (33), Message="Warning: File lock violation: C:\Documents and Settings\erik\Local Settings\Application Data\Microsoft\Outlook\Microsoft\Outlook\mailbox.pst"

This error message is actually from Windows, ZipBuilder just passes it on. Here is the actual message:

ERROR_LOCK_VIOLATION 33: "The process cannot access the file because another process has locked a portion of the file."

You can use a tool like Unlocker (http://ccollomb.free.fr/unlocker/ ) to find out which program has a lock on the file mailbox.pst.

Finding out which program is locking a file does not make it possible for Abakt to archive this file, it merely helps you finding the cause for the error message.