Observe Field :with Parameter Lost on Quick Re-Select

I am using an :observe_field on a series of select elements. It is
pretty successful. There is one bug with it that is killing me
though. When I change the option in a select, the :with parameter is
sent, the next element is updated, and everything is good.

Processing IpController#select_technology (for 0.0.0.0 at 2007-09-27
11:31:39) [POST]
   Session ID: c2e7072af4526b7b7a617e526e3d161b
   Parameters: {"ip_info_vw_ring_technology_key"=>"1",
"action"=>"select_technology", "controller"=>"ip"}
The actual tech key is 1
The session tech key is 1

If I change the option in the first select again, quickly (2 seconds
later), the action sent to the controller does not contain the :with
parameter.

Processing IpController#select_technology (for 0.0.0.0 at 2007-09-27
11:31:41) [POST]
   Session ID: c2e7072af4526b7b7a617e526e3d161b
   Parameters: {"action"=>"select_technology", "controller"=>"ip"}
The actual tech key is 0
The session tech key is 0

If I wat a little longer between changing options (6-7 seconds), it
behaves correctly. Is this a bug anyone else has seen? It is
maddening!

Thanks for your help,

Christian