What size is the image? It may be too large for the school computer's GPU to be able to handle as a texture. If so, you can always try loading it as a memory bitmap rather than as a video bitmap.

al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);

memory bitmaps are stored in normal RAM

video bitmaps are stored in RAM on the gfx card

Memory bitmaps are slower to use, but can be larger than the default video bitmaps.

Thus, you should try to load images as a regular video bitmap. If a large image fails to load, then you can load it as a memory bitmap instead. But you should detect that at run time, so that better computers will not use memory bitmaps when they could be using hardware accelerated ones.

Post your code with image then.

Windows doesn't like to run your executable from the directory you think it should be, so when you try to use a relative path like you are, it will be relative to whatever windows has set as the current working directory, not the one you think it is.

First try using an abosolute path to your files, then play with the al_get_standard_path to locate your files.

On Windows, make sure the data is stored relative to the exe

ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
al_append_path_component(path, "Media");
al_set_path_filename(path, "foo.png");

// a hack, but this probably works in place of the 'append':
// al_set_path_filename(path, "Media/foo.png");

al_load_bitmap(al_path_cstr(path, '/'));

The above code assumes the image is in a folder called 'Media' next to the executable. The documentation explains this clearly:

It's a hack, because you're abusing the structure a bit. An Allegro path is a vector of path components, eg: "usr", "share", "mygame". Then it has a filename: "img.png".

When you call al_path_cstr(), it joins them together with the delimiter you supply.

So if you add something like "foo/bar" via al_append_path_component() or al_set_path_filename(), you are putting two pieces together in a single slot of the vector.

It doesn't really matter in that when you call al_path_cstr() you'll get the same result. However, you cannot traverse each component individually now, since Allegro will treat your "combo" component as a single entity.

I doubt the functionality will ever change, so it should be safe to use.

Make sure you are calling al_init() first.

You can also do it this way:

ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
al_change_directory(al_path_cstr(path), '/');
al_destroy_path(path);

foo1 = al_load_bitmap("images/foo1.png");
foo2 = al_load_bitmap("images/foo2.png");

It still doesn't work after doing the thing with the paths.