[AD] crash! unhandled exception wip414 win2k msvc

[aj <aj@xxxxxxxxxx>]

wip414
win2k
msvc 6.0
release & debug builds.

i run my allegro app in windowed mode.
using the 'DirectX Windowed' driver.

i get an unhandled exception error when  i hit the msWindows task bars 
'show desktop' icon (that one near the Start button).
or sometimes i get an error saying  "The instruction at '0x0...' referenced 
memory at '0x0...', The memory could not be "read".

this error was repeatable...

in debug lib,  the error occurs here:

( the  '--->'  at start of line  indicates what msvc's debugger is pointing at)


__colorconv_blit_16_to_32:
005BF83C   mov         eax,[_cpu_capabilities (00c6e724)]
005BF841   and         eax,4
005BF844   je          __colorconv_blit_15_to_24+0F0h (005c0008)
005BF84A   push        ebp
005BF84B   mov         ebp,esp
005BF84D   push        ebx
005BF84E   push        esi
005BF84F   push        edi
005BF850   mov         esi,7E0h
005BF855   movd        mm3,esi
005BF858   punpckldq   mm3,mm3
005BF85B   mov         esi,0F800h
005BF860   movd        mm4,esi
005BF863   punpckldq   mm4,mm4
005BF866   mov         esi,1Fh
005BF86B   movd        mm5,esi
005BF86E   punpckldq   mm5,mm5
005BF871   mov         esi,dword ptr [ebp+8]
005BF874   mov         ecx,dword ptr [esi]
005BF877   mov         edx,dword ptr [esi+4]
005BF87A   mov         eax,dword ptr [esi+8]
005BF87D   mov         esi,dword ptr [esi+0Ch]
005BF880   add         ecx,ecx
005BF882   sub         eax,ecx
005BF884   mov         edi,dword ptr [ebp+0Ch]
005BF887   add         ecx,ecx
005BF889   mov         ebx,dword ptr [edi+8]
005BF88C   mov         edi,dword ptr [edi+0Ch]
005BF88F   sub         ebx,ecx
005BF891   shr         ecx,2
005BF894   mov         ebp,ecx
005BF896   mov         esi,esi
005BF898   shr         ecx,1
005BF89A   mov         esi,esi
---> 005BF89C   movd        mm0,dword ptr [esi]
005BF89F   punpcklwd   mm0,mm0