I have the same problem. Although in my case RA just crashes to the desktop. My GPU has support for GL version 4.4 so i don’t think that is the problem. I tried Dead or Alive 2 and SoulCalibur (Redump). The bios files matches the hash found here https://github.com/retropie/retropie-setup/wiki/Dreamcast
Capabilities: MMX MMXEXT SSE1 SSE2 SSE3 SSSE3 SSE4 SSE4.2 AVX AES
Built: May 31 2017
RetroArch [INFO] :: Version: 1.6.0
RetroArch [INFO] :: Git: 1056027
RetroArch [INFO] :: =================================================
RetroArch [INFO] :: Loading dynamic libretro core from: "C:\Emulators\RetroArch\cores\redream_libretro.dll"
RetroArch [INFO] :: [overrides] no core-specific overrides found at C:\Emulators\RetroArch\config\redream\redream.cfg.
RetroArch [INFO] :: [overrides] no game-specific overrides found at C:\Emulators\RetroArch\config\redream\Dead or Alive 2 (USA).cfg.
RetroArch [INFO] :: Shaders: preset directory: C:\Emulators\RetroArch\shaders\presets
RetroArch [INFO] :: Shaders: no game-specific preset found at C:\Emulators\RetroArch\shaders\presets\redream\Dead or Alive 2 (USA).cgp.
RetroArch [INFO] :: Shaders: no game-specific preset found at C:\Emulators\RetroArch\shaders\presets\redream\Dead or Alive 2 (USA).glslp.
RetroArch [INFO] :: Shaders: no core-specific preset found at C:\Emulators\RetroArch\shaders\presets\redream\redream.cgp.
RetroArch [INFO] :: Shaders: no core-specific preset found at C:\Emulators\RetroArch\shaders\presets\redream\redream.glslp.
RetroArch [INFO] :: Environ SET_VARIABLES.
RetroArch [INFO] :: Remaps: remap directory: C:\Emulators\RetroArch\config\remaps
RetroArch [INFO] :: Remaps: no game-specific remap found at C:\Emulators\RetroArch\config\remaps\redream\Dead or Alive 2 (USA).rmp.
RetroArch [INFO] :: Remaps: no core-specific remap found at C:\Emulators\RetroArch\config\remaps\redream\redream.rmp.
RetroArch [INFO] :: Redirecting save file to "C:\Emulators\RetroArch\saves\redream\Dead or Alive 2 (USA).srm".
RetroArch [INFO] :: Redirecting savestate to "C:\Emulators\RetroArch\states\Dead or Alive 2 (USA).state".
RetroArch [INFO] :: Environ SYSTEM_DIRECTORY: "C:\Emulators\RetroArch\system".
RetroArch [INFO] :: Environ GET_LOG_INTERFACE.
RetroArch [INFO] :: Content loading skipped. Implementation will load it on its own.
RetroArch [INFO] :: Environ GET_VARIABLE redream_resolution:
RetroArch [INFO] :: 640x480
RetroArch [INFO] :: Environ SET_INPUT_DESCRIPTORS:
RetroArch [INFO] :: RetroPad, User 1, Button "B (bottom)" => "A"
RetroArch [INFO] :: RetroPad, User 1, Button "Y (left)" => "X"
RetroArch [INFO] :: RetroPad, User 1, Button "Start" => "Start"
RetroArch [INFO] :: RetroPad, User 1, Button "D-Pad Up" => "D-Pad Up"
RetroArch [INFO] :: RetroPad, User 1, Button "D-Pad Down" => "D-Pad Down"
RetroArch [INFO] :: RetroPad, User 1, Button "D-Pad Left" => "D-Pad Left"
RetroArch [INFO] :: RetroPad, User 1, Button "D-Pad Right" => "D-Pad Right"
RetroArch [INFO] :: RetroPad, User 1, Button "A (right)" => "B"
RetroArch [INFO] :: RetroPad, User 1, Button "X (up)" => "Y"
RetroArch [INFO] :: RetroPad, User 1, Button "L2" => "L"
RetroArch [INFO] :: RetroPad, User 1, Button "R2" => "R"
RetroArch [INFO] :: Environ SET_HW_RENDER.
RetroArch [INFO] :: Requesting core OpenGL context (3.3).
RetroArch [libretro INFO] :: boot_load_rom loaded 'C:\Emulators\RetroArch\system\dc\dc_boot.bin'
RetroArch [libretro WARN] :: failed to open flash rom 'C:\Emulators\RetroArch\system\dc\flash.bin'
RetroArch [libretro INFO] :: pvr_reconfigure_spg mode=VGA pixel_clock=13500000 line_clock=15734 vcount=262 hcount=857 interlace=0 vbstart=260 vbend=336
RetroArch [libretro INFO] :: bios_validate_flash resetting FLASH_PT_FACTORY
RetroArch [libretro INFO] :: bios_validate_flash resetting FLASH_PT_USER
RetroArch [libretro INFO] :: bios_validate_flash resetting FLASH_PT_GAME
RetroArch [libretro INFO] :: bios_validate_flash resetting FLASH_PT_UNKNOWN
RetroArch [libretro INFO] :: loading D:\Games\Sega - Dreamcast\Dead or Alive 2 (USA).gdi
RetroArch [libretro WARN] :: failed to load D:\Games\Sega - Dreamcast\Dead or Alive 2 (USA).gdi
RetroArch [ERROR] :: Failed to load content.
RetroArch [INFO] :: Environ SET_PIXEL_FORMAT: RGB565.
RetroArch [INFO] :: Redirecting save file to "C:\Emulators\RetroArch\saves\Dead or Alive 2 (USA).srm".
RetroArch [INFO] :: Redirecting savestate to "C:\Emulators\RetroArch\states\Dead or Alive 2 (USA).state".
RetroArch [INFO] :: Version of libretro API: 1
RetroArch [INFO] :: Compiled against API: 1
RetroArch [INFO] :: [Audio]: Set audio input rate to: 29986.80 Hz.
RetroArch [INFO] :: Found shader "C:\Emulators\RetroArch\shaders\retroarch.cgp"
RetroArch [INFO] :: [Video]: Video @ fullscreen
RetroArch [INFO] :: [Video]: Using HW render, OpenGL driver forced.
RetroArch [INFO] :: [GL]: Found GL context: wgl
RetroArch [INFO] :: [GL]: Detecting screen resolution 2560x1600.
RetroArch [INFO] :: [WGL]: wglSwapInterval(1)
RetroArch [INFO] :: [GL]: Vendor: NVIDIA Corporation, Renderer: GeForce GTX 780 Ti/PCIe/SSE2.
RetroArch [INFO] :: [GL]: Version: 3.3.0 NVIDIA 382.53.
RetroArch [INFO] :: [GL]: Using Core GL context.
RetroArch [INFO] :: [GL]: Using ARB_sync to reduce latency.
RetroArch [INFO] :: [GL]: Using resolution 2560x1600
RetroArch [INFO] :: [GL]: Default shader backend found: glsl.
RetroArch [INFO] :: [Shader driver]: Using Cg shader backend.
RetroArch [ERROR] :: Invalid profile type
RetroArch [INFO] :: [CG]: Destroying programs.
RetroArch [ERROR] :: [GL]: Failed to initialize shader, falling back to stock.
RetroArch [INFO] :: [Shader driver]: Using Cg shader backend.
RetroArch [ERROR] :: Invalid profile type
RetroArch [INFO] :: [CG]: Destroying programs.
RetroArch [ERROR] :: [GL]: Shader initialization failed.
RetroArch [ERROR] :: [Video]: Cannot open video driver ... Exiting ...
RetroArch [ERROR] :: Fatal error received in: "init_video()"
RetroArch [ERROR] :: This core requires a content file.