can’t widgetize theme

hi there,
i recently installed the vSlider theme which very nicely integrates WP2 (here 2.0.2) and Gallery2 (2.1.1). Unfortunately vSlider doesn’t provide Widget support. I checked out the Automattic homepage and it looks fairly easy to widgetise a theme. I added the lines in the functions.php to register the widgets menu point in the admin area and it works. But if I try to change stuff in the widget admin area nothing works. The box “Sidebar 1” shows a textbox with the standard text “Your theme will display its usual sidbar ….” and under that half covered I can see one element from my former Sidebar1 which i used with my old theme. Drag&Drop of elements into the Sidebar or out of the sidebar doesn’t work. I am using FF 1.5.0.2, in IE 6 the situation is hardly different. Only difference is, that the elements of Sidebar one are not covered by the textbox.

Any ideas what I need to do to fix this ?

Cheers
Martin