Matrox video driver - Bugcheck at Explorer start

The Matrox Mystique display card is basically compatible with Reactos as Desktop
is displayed successfully and the Start menu is working fine also.
Reactos was built following a CVS update on 08032004 (DBG=1 KDBG=1)

A bugcheck (Ros crash) is reproductible in my real hardware configuration (
matrox mystique ISA display card + mga64 NT4 driver from matrox.com) when
explorer is started from "My Computer" or Start/Explorer shortcut at the opening
of the "explorer" window.

-----------Debugport messages -----------------
(shlview.c:1478:ShellView_OnNotify) – a00053f0 WM_COMMAND fffffffe unhandled
(io/create.c:148) Failed to mount logical volume (Status c000014f)
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(objects/dc.c:1462) GDI object type 0x000a0000 not implemented
(shlview.c:1478:ShellView_OnNotify) – a000c9a8 WM_COMMAND ffffff98 unhandled
(compobj.c:1488:CoCreateInstance) no classfactory created for CLSID
<guid-0x25d0>, hres is 0x80040154
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
(misc/object.c:98) Invalid handle 0x610066
Entered debugger on exception number 14.
Entered kernel debugger (type "help" for a list of commands)
kdb:> bugcheck
KeBugCheck at dbg/kdb.c:894
(videoprt.c:125) VideoPortGetBusData
(videoprt.c:862) VideoPortSetBusData
Bug detected (code 1 param 0 0 0 0)
APC_INDEX_MISMATCH
Pid: 8 <explorer> Thrd: c1efccc0 Tid: 2f
Frames: <ntoskrnl.exe: befb>
<ntoskrnl.exe: 35f8a>
<ntoskrnl.exe: 36131>
<ntoskrnl.exe: 36204>
<ntoskrnl.exe: 3622f>
<ntoskrnl.exe: 362a1>
<ntoskrnl.exe: c17c>
<ntoskrnl.exe: 14ab>
<ntoskrnl.exe: 1e76>
<ntoskrnl.exe: 3b11>
<mga64ddi.DLL: 5e4d>
Page fault at high IRQL was 2
Entered debugger on exception number 14.
Entered kernel debugger (type "help" for a list of commands)
kdb:>