The only way I've been able to reproduce that error on my system was by renaming/deleting my Index.ini file from a mod. Upload abortscreen.bmp (as a .png file, to keep filesize down), maybe that will give us a clue. What I can suggest, short of uploading the mod so I can take a look, is to make sure the Index is there, with no typos in the file name.
As an example, here's what my abortscreen.bmp looks like when I try to load a mod with no Index.ini (Megashoe.rte).