Xerox Phaser 8400DX issues

Hello,
I have been experiancing IPP issues with Vista clients connecting to a Xerox
Phaser 8400DX connected to an SBS 2003 domian for some time now. All XP
clients connect over the internet just fine. Some of the Vista client
machines connect and operate just fine and some just refuse indicating
"connection faild invalid printer name" very frustrating.
Recently a Vista Business Client machine which is a member of the SBS 2003
domain locally where the Xerox is connected to the server with a static local
IP just stopped allowing print jobs and crashing explorer giving this error
"Function Address 0x3dd1c252 caused a production fault. (exception
code0x0000005) some or all property pages may not be displayed".
Any wisdom on either issue?

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RH