Thanks for spearheading this issue, Froggy. I, too, have tried the "light" dll files and still get load errors with hi-res maps, even though I can use hi-res and 24bit aircraft skins.
EDIT: here's my conf.ini if it helps anyone
[il2]
title=Il2-Sturmovik Forgotten Battles
hotkeys=HotKey game
[window]
width=1280
height=1024
ColourBits=32
DepthBits=24
StencilBits=8
ChangeScreenRes=1
FullScreen=1
DrawIfNotFocused=0
EnableResize=0
EnableClose=1
SaveAspect=0
Use3Renders=0
WideScreenFoV=1
UIColor=4
UIDetail=0
UIBackground=en
[GLPROVIDER]
GL=Opengl32.dll
[GLPROVIDERS]
Open GL=Opengl32.dll
DirectX=dx8wrap.dll
[NET]
speed=100000
routeChannels=0
serverChannels=31
localPort=21000
remotePort=21000
SkinDownload=1
serverName=No Name
serverDescription=
remoteHost=
localHost=
socksHost=
checkServerTimeSpeed=1
checkClientTimeSpeed=0
disableNetStatStatistics=0
showPilotNumber=1
showPilotPing=1
showPilotName=1
showPilotScore=1
showTeamScore=0
cumulativeTeamScore=0
showPilotArmy=1
showPilotACDesignation=1
showPilotACType=1
filterUserNames=0
reflyKIADelay=0
maxAllowedKIA=-1
reflyKIADelayMultiplier=0.0
reflyDisabled=0
allowMorseAsText=1
allowCustomSounds=1
[MaxLag]
farMaxLagTime=10.0
nearMaxLagTime=2.0
cheaterWarningDelay=5.0
cheaterWarningNum=-1
[chat]
region=(dx=0.6925,dy=0.071666665,x=0.0,y=0.0)
[game]
ClearCache=0
Arcade=0
HighGore=1
mapPadX=0.5925293
mapPadY=-0.0078125
viewSet=57
Intro=0
NoSubTitles=0
NoChatter=0
NoHudLog=0
NoLensFlare=0
iconTypes=3
eventlog=eventlog.lst
eventlogkeep=0
3dgunners=1
TypeClouds=1
ScreenshotType=1
jpgQuality=1.0
RecordingIndicator=1
MapAlpha=0.99
SaveTrk=1
IconUnits=0
SkipParatrooperViews=0
NoMissionInfoHud=0
noKillInfoHud=0
BlockMorseChat=0
SmallMapWPLabels=1
ShowMorseAsText=1
[HotKey game]
PrintScreen=ScreenShot
P=pause
Pause=pause
[HotKey gui]
Escape=activate
[HookViewFly Config]
timeFirstStep=2.0
deltaZ=10.0
[HookView]
MouseLeft=Len
[HookView Config]
AzimutSpeed=0.1
TangageSpeed=0.1
LenSpeed=1.0
MinLen=1.0
DefaultLen=20.0
MaxLen=3000.0
Speed=6
LeanF=0.39
LeanS=0.39
Raise=0.2
RubberBand=0.5
[HotKey builder]
MouseLeft=objectMove
MouseRight=popupmenu
Enter=freeView
Shift MouseLeft=worldZoom
Alt MouseLeft=select+
Alt MouseRight=select-
Alt Ctrl=unselect
PageDown=change+
PageUp=change-
End=change++
Home=change--
Ctrl MouseLeft=insert+
Insert=insert+
NumPad-0=insert+
F=fill
Ctrl MouseRight=delete+
NumPad.=delete+
Delete=delete+
Backspace=cursor
Tab=cursor
F10=land
F11=onLand
NumPad-=normalLand
NumPad+=toLand
NumPad-5=resetAngles
NumPad-8=resetTangage90
NumPad-7=stepAzimut-5
NumPad-4=stepAzimut-15
NumPad-1=stepAzimut-30
NumPad-9=stepAzimut5
NumPad-6=stepAzimut15
NumPad-3=stepAzimut30
[MouseXYZ]
F1=SpeedSlow
F2=SpeedNormal
F3=SpeedFast
MouseRight=XYmove
F4 MouseRight=Zmove
MouseMiddle=Amove
F5 MouseRight=Amove
F6 MouseRight=Tmove
F7 MouseRight=Kmove
[MouseXYZ Config]
RealTime=1
[HotKey Console]
Shift Tab=Activate
[Console]
HISTORY=1024
HISTORYCMD=1024
LOAD=console.cmd
SAVE=console.cmd
LOG=0
LOGTIME=0
LOGFILE=log.lst
LOGKEEP=1
[sound]
SoundUse=1
SoundEngine=1
Speakers=0
Placement=0
SoundFlags.reversestereo=0
RadioFlags.Enabled=1
RadioEngine=2
MusicVolume=8
ObjectVolume=7
MusState.takeoff=1
MusState.inflight=1
MusState.crash=1
MusFlags.play=0
MasterVolume=11
Attenuation=7
SoundMode=1
SamplingRate=2
NumChannels=2
SoundExt.occlusions=0
SoundFlags.hardware=1
SoundFlags.streams=1
SoundFlags.duplex=1
SoundExt.acoustics=0
SoundExt.volumefx=0
SoundFlags.voicemgr=0
SoundFlags.static=1
VoiceVolume=10
Channels=2
SoundExt.extrender=0
SoundFlags.bugscorrect=0
SoundSetupId=8
ActivationLevel=0.02
Preemphasis=0.85
RadioLatency=0.5
AGC=1
PTTMode=1
SoundFlags.UseRadioChatter=0
SoundFlags.AutoActivation=0
RadioFlags.PTTMode=0
RadioFlags.PlayClicks=0
ActLevel=0
MicLevel=0
SoundFlags.forceEAX1=0
[rts]
;ProcessAffinityMask=1
mouseUse=2
joyUse=1
trackIRUse=1
DisableIME=0
locale=
UseSmartAxis=0
[rts_mouse]
SensitivityX=1.0
SensitivityY=1.0
Invert=0
[rts_joystick]
X=0 1 4 9 16 25 36 49 64 81 100 0
Y=0 1 4 9 16 25 36 49 64 81 100 0
Z=0 10 20 30 40 50 60 70 80 90 100
RZ=0 10 20 30 40 50 60 70 80 90 100 0
FF=0
U=0 10 20 30 40 50 60 70 80 90 100 0
V=0 10 20 30 40 50 60 70 80 90 100 0
[Render_DirectX]
TexQual=3
TexMipFilter=2
TexCompress=0
TexFlags.UseDither=1
TexFlags.UseAlpha=0
TexFlags.UseIndex=0
TexFlags.PolygonStipple=1
TexFlags.UseClampedSprites=0
TexFlags.DrawLandByTriangles=1
TexFlags.UseVertexArrays=1
TexFlags.DisableAPIExtensions=0
TexFlags.ARBMultitextureExt=1
TexFlags.TexEnvCombineExt=1
TexFlags.SecondaryColorExt=1
TexFlags.VertexArrayExt=1
TexFlags.ClipHintExt=0
TexFlags.UsePaletteExt=0
TexFlags.TexAnisotropicExt=0
TexFlags.TexCompressARBExt=1
TexFlags.TexEnvCombine4NV=0
TexFlags.TexEnvCombineDot3=0
TexFlags.DepthClampNV=0
TexFlags.SeparateSpecular=0
TexFlags.TextureShaderNV=0
HardwareShaders=0
Shadows=2
Specular=2
SpecularLight=2
DiffuseLight=2
DynamicalLights=1
MeshDetail=2
VisibilityDistance=3
Sky=2
Forest=2
LandShading=3
LandDetails=2
LandGeom=2
TexLarge=1
TexLandQual=3
TexLandLarge=1
VideoSetupId=4
ForceShaders1x=0
PolygonOffsetFactor=-0.15
PolygonOffsetUnits=-3.0
[Render_OpenGL]
TexQual=3
TexMipFilter=3
TexCompress=0
TexFlags.UseDither=0
TexFlags.UseAlpha=0
TexFlags.UseIndex=0
TexFlags.PolygonStipple=0
TexFlags.UseClampedSprites=0
TexFlags.DrawLandByTriangles=0
TexFlags.UseVertexArrays=0
TexFlags.DisableAPIExtensions=0
TexFlags.ARBMultitextureExt=1
TexFlags.TexEnvCombineExt=1
TexFlags.SecondaryColorExt=1
TexFlags.VertexArrayExt=0
TexFlags.ClipHintExt=1
TexFlags.UsePaletteExt=1
TexFlags.TexAnisotropicExt=1
TexFlags.TexCompressARBExt=0
TexFlags.TexEnvCombine4NV=0
TexFlags.TexEnvCombineDot3=1
TexFlags.DepthClampNV=0
TexFlags.SeparateSpecular=1
TexFlags.TextureShaderNV=0
HardwareShaders=1
FogLow=1
FogHaze=4
Shadows=2
Specular=2
SpecularLight=2
DiffuseLight=2
DynamicalLights=1
MeshDetail=2
VisibilityDistance=3
Sky=2
Forest=3
LandShading=3
LandDetails=2
LandGeom=3
TexLarge=1
TexLandQual=3
TexLandLarge=1
VideoSetupId=17
Water=2
Effects=2
ForceShaders1x=0
PolygonOffsetFactor=-0.0625
PolygonOffsetUnits=-1.0
[Mods]
RandomSplash=1
netCallsign=
[QMB]
PlaneList=0
EDIT: I'm running 4.12.2 with ModAct 5.3, and have an AMD (ATI) HD7900 card