Hi old man,
Since you are unable to preview your listings when using Firefox, I suspect you must have a pop-up blocker enabled on your browser that is preventing the preview window from displaying. It is most likely that the culprit is the default Firefox pop-up blockers, however, browser toolbars such as those offered by Yahoo and Google also come with pop-up blockers that are enabled by default.
You can find instructions on how to disable the most common pop-up blockers on the following website: http://de.usa.edu/HowTo/How2PopupBlockers.html. Once you have disabled all the pop-up blockers that may be enabled on your browser, you should be able to use the "Preview" option within Auctiva. The only browser we fully support for Mac OS is Firefox, so you should definitely continue using that browser.
If you have any additional questions or concerns, please feel free to contact our customer support team by completing the web form on the following page of our site: http://www.auctiva.com/help/requesthelp.aspx
-Mike