autocomplete fails after several times when theme is changed

autocomplete fails after several times when theme is changed

using jqueryui 1.9.2.  i have an autocomplete box in a jqueryui dialog.  i'm trying change the theme with theme roller and added ref to jquery-ui-1.9.2.custom.css <link rel="stylesheet" type="text/css" href="/Content/themes/start/jquery-ui-1.9.2.custom.css" />).  just by adding this ref the autocomplete fails after several times, i.e. it works fine usually twice then fails to show any items unless i refresh the page.  if i remove the ref to the css it works fine until im blue in the face.  This behaviour is consistent across different browsers: firefox, ie.

i know that css is not javascript and there SHOULD be no reason why the css file would cause it to fail, but the fact remains that simply adding this reference IS causing it to fail, and without the reference it works fine. 

the only thing i can think of is that by adding the ref, jqueryui is looking somewhere else for autocomplete.js or some other component?? i'm not sure.  any ideas anyone?