When I try to execute any program compiled with allegro (allegro examples included), i get a message that says: 'Error: couldn't set GFX_SAFE' or 'Error: there's not an apropriate device for the resolution specified' or something like that (i'm sorry i cannot remember the exact messages :(.
As I noted that I could reach that resolution (tested with DirectX SDK samples and even with allegro itself) I wondered why the heck did that happen. I have tracked the bug, with a debug version of allegro and gdb, down to the function 'gfx_directx_create_surface' after being called by 'create_primary'. The problem seems to arise when the function tries to create the primary surface for the display. In fact I get the DDERR_NODIRECTDRAW message, which means that I do not have a DirectDraw capable driver.
I am using a rather old graphic card (and computer :( but every other program seems to work perfectly with that card.
My computer is an AMD 5x86 133Mhz with 32Mo RAM, 4GB HD, 70MB of swap partition, and a Trident TGUI9440 with 1 MB of video memory.
Ok, I will try to help you:
Which version of Allegro are you using ?
Which version of DirectDraw ?
Which version of Windows ?
There is a new graphic mode detection code in the CVS tree. Could you try it ?