My roommate has an interesting but, which I'm not sure how to fix.
Any auction listed, instantly cancels, which puts the item into the mailbox.
But he's still out the listing fee.
The only auction related addon is Auctioneer.
It's the latest version.
*Edit*
He gets the same results with all addons disabled.
This is a clean/fresh install of warcraft (just formatted and installed Win7).