Oh, g*d. Anytime you mix the CF UI stuff (CFSELECT, CFFORM, etc.) with custom JavaScript (including using jQuery) you are asking for pain. The CF UI stuff is based on old EXT-JS 2.0 libraries, and don't play well with others.
That said, what does the FORM or CFFORM tag look like? And how about the button or control that initiates the populateBills() function?
-Carl V.