This error can also happen in the following two scenerios:
1. When a virus scan product is recently installed on the Exchange server and an initial "full store" scan is not performed. The virus scan tries to scan every message that you try to archive and it cannot keep up so it gives the error message. The solution is for the system administrator to run a full information store scan.
2. Your archive file or a folder in your archive file is too large. Each folder in a .pst file can contain a maximum of 16,384 items and the total file size of a .pst file cannot exceed 2 Gigabytes (GB). If an archive reaches 16,384 items or 2gb, a person will not be able to archive either to to a certain folder or to their entire archive any longer. Solution: If the file is 2 gigs, rename their old archive file (to something like archive1.pst) and re-run archiving again. This will create a new archive.pst file. In the case of a folder having 16,383 items, you can just rename that folder inside of the archive and when the archive program runs, it will create a new folder.