I'm fairly new to Zenphoto and all. I've put up some albums and want to provide slideshows. Now the slideshows work, but the first time you view it, you see the fading transition, then the same picture you already saw, but with the annoying loader circle animation through it, until it goes on to the next picture. When you view the slideshow again, it behaves like you would expect it to. Until you empty your local browser cache.

I did precache all of my pictures in Zenphoto. It happens in IE 8 as well as Firefox 3.6. I'm not sure whether it is an issue of Zenphoto and the included slideshow feature or if it has to do with the fact that I downloaded and installed this slideshow plugin:
http://www.deltawebdev.co.uk/projects/zenphotoSlideshowFlash.
Under Options > Plugin, I see a Slideshow section and a Slideshow Flash section. The latter has an exclamation mark sitting next to it, with a message saying: "NOTE: Instantiating the option interface within the plugin may cause performance issues. You should instead set $option_interface to the name of the class as a string." Not sure if this has to do with the unwanted Flowplayer behaviour.

Does someone happen to know what I did wrong and how I can fix it?

I'm not sure what more info I should provide. Should I provide a link to one of my albums? PHP version? Zenphoto version is 1.3.1.2 [6407]. Theme is Zenpage.

The NOTE message is simply telling you that this plugin is conforming to the older plugin interface model. We had discovered in the development of the current version of Zenphoto (which you are using) that loading these options interface objects is quite costly and not needed except when the on the admin options pages. You can ignore the message if you wish. Or you can edit the line that sets $option_interface so that it sets it to the quoted name of the function. Normally this is just replacing the text "new" by an opening quote and the pair of parens at the end by the closing quote always insuring that there are not any leading or trailing spaces.

As to the functioning of the plugin, I will have to leave response to its author.

Thank you for your swift response, Stephen. I have now disabled the plugin called slideshow_flash, so now I have only 'slideshow v1.4.0' (written by you, acrylian and dpeterson) enabled. The slideshow still behaves the way I described.
I have fiddled with speed and timeout values under Options > Plugin but that doesn't seem to make a difference.
I have also tried JQuery Cycle and JQuery Colorbox modes, but those give me other types of faulty behaviour (one only shows about 50 px of the height of photos and the other shows the pictures in original resolution, which is way bigger than my screen). :-S

but the first time you view it, you see the fading transition, then the same picture you already saw, but with the annoying loader circle animation through it, until it goes on to the next picture. When you view the slideshow again, it behaves like you would expect it to. Until you empty your local browser cache.

This would indicate a performance issue with your server and/or internet connection. Naturally the slide show must obtain the images from the server before it can display them if they are not in its cache.

As to the size of the colorbox mode slideshow, that is an option that you can set.

The colorbox mode has two option, for the sized image for that you can set the size and the full image which is by default scaled with the colorbox depending on the current window size.

The precaching does not cover these images at all (only standard images on the theme like thumbs if not using custom size functions). So depending on your server's power and the dimensions of the images it might take some time to generate the sized image. This may lead to "glitches" in the slideshow display. Simply because the server takes longer to generate it than the slideshow actually stays on a slide.

Flowplayer mode actually uses the full image without processing and cache normally but since with 1.4.0 all images are cached it might cause similar issues.