Jitter when using slideUp

Jitter when using slideUp

Hello.  I have a page with three clickable hotspots.  Once one of these elements is clicked, one of the two forms is appended to it and is revealed using slideDown.  If I click on a different hotspot, the currently open spot slides up and the new form slides down in a new location.  here's an example url:


However, on PC in Firefox, when the form slides up it causes elements below it to jitter like crazy.  No such behavior is observed in other browsers including IE7 and 8.  It also works fine on Mac version of FF.  

Any ideas what might be causing this jitter?  I'ce been batting at it for the last three days with no apparent success, so any input would be very appreciated.

Thanks!
Luka