I E 9 tries to use a cached PAC file when users are away from corporate network

We just bit the bullet and upgraded our 400+ desktops/laptops to IE 9.  Internally we use a PAC file hosted on a local server for proxy redirection.  Some of my users are not able to browse the internet when they take their laptop home.  I figured out that if I go to Internet Options and Delete Temp Internet Files/Cookies/History and then close my browser and reopen it, they can now browser with no issue. 

I have tried setting the EnableAutoproxyResultCache and BadProxyExpiresTime and it still doesn't work.

Any suggestions would be greatly appreciated.