Can't run slideshow with fullscreen applet under Firefox

Just switched to Firefox from IE and now my Gallery slideshow won't run via fullscreen applet. The Java applet loads fine, I get the 'Slideshow progression' dialog but just when I think the slideshow is going to start I get this error:

Gallery Remote can find no protocol implementation at the URL http://www.earthdreaming.net/gallery/.
Check with a web browser that http://www.earthdreaming.net/gallery is a valid Gallery URL.

Looking in the Java Console when running Firefox, I see:

13720|TRACE|GalComm |Trying protocol 2 for http://www.earthdreaming.net/gallery/
13760|TRACE|GalComm |Sending cookie: PHPSESSID=ead1cecb43aa17544f5e519f4dfc8f1a; path=/; domain=.www.earthdreaming.net
14742|ERROR|GalComm |java.net.ConnectException: Connection refused: connect

[and later:]

14742|TRACE|GalComm |Trying protocol 2.5 for http://www.earthdreaming.net/gallery/
14752|TRACE|GalComm |Sending cookie: PHPSESSID=ead1cecb43aa17544f5e519f4dfc8f1a; path=/; domain=.www.earthdreaming.net
15743|ERROR|GalComm |java.net.ConnectException: Connection refused: connect

After sending this cookie under IE, Java Console says:
18066|TRACE|GalComm |Server has protocol 2

Any thoughts? Thanks.

Gallery URL: http://www.earthdreaming.net/gallery
Gallery version: 1.4.4-pl6
Apache version: 1.3.33 (Unix)
PHP version: 4.3.10
Graphics Toolkit: ImageMagick
Operating system: Win2000
Web browser/version: Firefox