I have discovered the problem... mine! I had turned off the javascript in Firefox because of another website's activity and when I viewed the 'page source' for your page I saw that these two activities call for javascript. I shall turn it back to On! :o) And...
All is back to normal when my javascript is on... And your smile returns! :o) The following is the original concern of this msg.

The next and previous page buttons are not working... one must click on the page number desired. :o)
This bug occurs in all galleries... I suppose... I tried a few of them! :o)
Also 'Show Users Online' is not working.
I am a Firefox user... v.3+ I just checked in with IE... all is fine in IE.
In Firefox you are displaying all the page numbers both above & below the page of pictures... As an aside... I was very happy to see this doesn't happen in IE! More work to do... you said DARN¿ :o)

It is all working for me Con.....empty your cache? etc? :=)
I am running IE 7....

It works for me under Firefox as well.

I use firefox and its fine with mine too