I have same config on 2 different types of hardware, one Sempron based, one Core Duo

Both lots are managed by same user/workstation policy

iPrint policy is on User Policy (as I could not get it working with workstation policy)

Both lots have same client 4.32 (will update soon)

Sempron based PC work just fine, no problems
The newer lot has serious problems

Printers can not be installed manual (see below) or are NOT pushed via policy

If I go in IE7 to /ipp page & select printer to install I can click OK & then IE hangs & the printer does NOT get installed

Apache log says - - [03/Sep/2008:00:14:31 +0100] "OPTIONS * HTTP/1.1" 200 - - - [03/Sep/2008:00:14:31 +0100] "POST /ipp/SCR-Mono-HPLJ4350 HTTP/1.1" 406 - - .xxxxxxxxxxxxxxx.xxxxxxxxxxx.xxxxxxx [03/Sep/2008:00:14:31 +0100] "POST /ipp/SCR-Mono-HPLJ4350 HTTP/1.1" 200 7057

So server side works just fine, but these clients have serious problem somewhere

Anybody an idea what it could be?