I am having this same darn thing happen to me. I even wrote Auctiva C/S about it yesterday. They told me that fixed price items default to 10 days. I wrote back and told them that it isn't happening to my "fixed price" - it's happening to my AUCTIONS. Still no word back yet, almost 24 hours later.
Guess we have to be extra careful. Yes, eBay got a lot more $$$ from me this week than they should have due to this Auctiva glitch!