I was browsing the Connect Forums this morning, and spotted a post that someone had given relating to PST Migrations - a current bane of mine, but that's a different story.
The article is :
It covers many MAPI error codes and where they might appear in Enterprise Vault, and also what might be the cause and remedial possibilities. One of the most common ones with PST Migrations is the 'corrupt store' message, which is error code 0x80040600. Usually this isn't that the PST is corrupt, but that something is stopping Outlook using Unicode PSTs or that the PST file is particularly 'close' to the 'old' 2 Gb limit of PSTs (when they were only available in ANSI format)