Hi DaveCandy,
Based on the content of the error you are receiving, it sounds like there is a "Features" section in the item specifics of the listing with several options underneath it and that you are checking more than 3 of those options when only 3 are allowed. I'd need to take a look at the specific listing to be sure though.
If that is indeed the case, I suspect you will be able to post this listing successfully once you have revised it such that no more than 3 options are checked under "Features" in the item specifics.
If you need further assistance with this issue, please feel free to contact our customer support team using the web form on the following page of our site:
http://www.auctiva.com/help/requesthelp.aspx-Mike