It is possible that there is a bug in Fast Dial 2.23b1 when used with Firefox 3.6

The symptom is that a new Background cannot be loaded into a theme where a background is already present

Bug first noted here

On my system , this bug is only apparent in Firefox 3.6

As the default setting in Themes has no background it is possible therefore to load a background into defaults.

However this is inconvenient, as the settings all have to be reset to match ones personal settings.

My suggestion as a temporary workaround is to create a template of all ones settings from defaults and save it as a theme (without a background) called template for example.

each time one wants to load a new background after that, go to Template, load background and then rename Template* with name of background.

addendum

It would appear that themes itself is not effected, so one can import a complete theme and the background is saved just fine...