P.S. That error was in the datepicker/jquery.bgiframe.js file. Additional errors on jquery.datePicker.js
Looks like a problem with IE6. If you get this error, you might want to consider running your admin console under Firefox. That worked for me.
I installed cformsII on top of a new 2.3.1 WordPress install. Getting an error when I try to go to the Global Settings tab, then that page crashes after clicking OK.