Nested sortables cause strange behavior in IE

Nested sortables cause strange behavior in IE

Having connected nested sortables seems to cause odd behavior in Internet Explorer(both 7 & 8).

Example here:
http://mastersite.sohowire.com/sortTest.php

To reproduce:
Drag 'cinco' or 'cuatro', and the entire green container and everything inside it disappears.  A double placeholder will show up, sometimes with a gap in between them (straddling other items).

I've tried to simplify the example, however the results seem to vary with more complicated implementations.  In my actual app, IE is deleting the entire sortable item that has the nested sortables inside it.