NW 6.5 sp7 w/ post iPrint server updates and latest 5.06 vista client.

From the iPrint web page, the correct 64-bit iPrint client is installed from
IE 7.

When a printer is selected for installation, the driver download begins and
then stops with a "print driver is unknown" error -2147023099

If I open the c:\NDPS\DRVR_TMP folder, and then the *.tmp file that was
downloaded from the iPrint server, the contents are actually the driver
assigned under the iPrint Vista-32 bit tab in iManager and not the driver
defined and assigned under the Vista-64 tab.

Any ideas of where to start?