XP Dual Core USB MIDI driver problem

Hi,

I manufacture a USB MIDI class device that works on many different PCs
running XP and MACs running OSX, but it does not work on 3 customer
machines that are all Intel Duo dual cores running XP. I have found
only one post on the web with the same issue with USB MIDI class
devices other than ours.

like here:
http://groups.google.com/group/micro...c43f5b82a5d0c8

But I have not been able to find a solution.

The device is found by the OS and is installed normally. It appears as
a USB composite device and as a USB Audio device, just like it does on
all other XP systems. The problem is that it is not installed as a
MIDI device in XP.

One customer was able to get our USB MIDI device to work after a clean
re-install of XP, but it stopped working after they installed the extra
drivers/ updates from the OEM disk.

systems with the problem so far:
1. Desktop Intel PD 805 Dual Core (2.66 Ghz ), motherboard is Abit NI8
SLI
2. Unknown Acer dual core laptop
3. Acer Aspire 5672 WLMi laptop

Can anyone suggest how I can get in touch with MS directly to solve
this?

thanks
Mike