I have the same issue, but it's intermittent.
http://goo.gl/vfQ3d
I posted multiple widgetkit modules (beta19) on the frontpage each containing a slideset and they refuse to load correctly the first attempt. each module only displays the first 2 slides instead of all 4 of them in the first slideset. If I reload they display correctly.
page load first attempt
http://img267.imageshack.us/img267/4271/ytslideset1.jpg
page load second attempt
http://img718.imageshack.us/img718/1161/ytslideset2.jpg
I can't tell if this is a javascript issue, a gantry issue, or multiple uses of widgetkit on the frontpage (one page). I use the widgetkit slideshow in the main position and 6 instances of slideset below it.
I see the following javascript files loading on first load
media/system/js/mootools-core.js
media/system/js/caption.js
media/widgetkit/js/jquery.js
cache/widgetkit/widgetkit-25944e5d.js
components/com_jfbconnect/includes/jfbconnect.js
media/system/js/mootools-more.js
libraries/gantry/js/gantry-buildspans.js
modules/mod_roknavmenu/themes/fusion/js/fusion.js
media/widgetkit/widgets/lightbox/js/lightbox.js?_=1325112888992
media/widgetkit/widgets/mediaplayer/mediaelement/mediaelement-and-player.js?_=1325112888994
media/widgetkit/widgets/spotlight/js/spotlight.js?_=1325112888995
connect.facebook.net/en_US/all.js
media/widgetkit/widgets/slideshow/js/slideshow.js?_=1325112889263
media/widgetkit/widgets/slideset/js/slideset.js?_=1325112889267