Hi themodo,
Ebay's Trust and Safety department has imposed several different listing restrictions for the holiday season and I am almost certain your listings are failing to post due to one of these. Please file a support case regarding this issue using the appropriate link on our help page:
http://www.auctiva.com/free_auction_software_help/help.aspx
Our support staff will be able to let you know what needs to be done to correct these listings.
-Mike