Hello all
I'm a new to Allegro, but not in game programming. I have a task to write a game, which can run on windows os even without video drivers (and without OpenGL). I took simple exhello example for experiments, but faced with a trouble When I start it in fullscreen autodetect mode, Allegro choose an DirectDraw Accel gfx driver, and then a simple frame of window appears (but it must be white background with a black text). Program main loop (readkey) seams works because I can quit axample with a keyboard. So just window is not updated after release_screen(). All DirectDraw tests of dxdiag works fine. Two strings I changed are:

set_color_depth(32)
set_gfx_mode(GFX_AUTODETECT, 800, 600, 0, 0)
Because it's standart video mode for this computer.

In log where is no error:
al-main INFO: Allegro initialised (instance 1)
al-gfx INFO: Called set_gfx_mode(0, 800, 600, 0, 0).
al-gfx INFO: First call, remembering console state.
al-gfx INFO: Autodetecting graphic driver.
al-gfx INFO: The driver will wait for vsync.
al-gfx INFO: set_gfx_card success for 800x600x32.
al-gfx INFO: Called set_gfx_mode(-1, 0, 0, 0, 0).
al-gfx INFO: Closing graphics driver (1013EF00) DirectDraw accel.
al-gfx INFO: Closing, restoring original console state.
al-gfx INFO: Graphic mode closed.

OS is WindowsXP Professional Service Pack 2. I also tried other examples, even in window mode examples windows not updated (I see background desktop of window).
I'm confused oO Allegro must work even without video drivers, is not it? Can you help me, please?

Added:
It's very strange... I started a virualbox and installed a copy of WindowsXP on it. Without drivers (using default vga.dll) only Page Flipping works fine! Situation above repeated with all examples except ex3buf and exflip (second part with page flipping). May be a bug in init of DirectDraw accel (default screen bitmap) with default vga drivers in windows?
P.S. Sorry for my English... I'm from Russia

DirectDraw Accel is already Fullscreen mode.
I'm sure that exhello clears screen and draws a text on it, because on my other computer this example works fine
Then I added a page flipping support in this example, then all start working