I have a series of tasks programmed in DirectRT. All .bmps (a lot, around 250) are located in the stim folder (there is no other way, right?). However, in one of the tasks, the same 8 .bmps are shown 6 times (randomly). At random times, one of the trials doesn't work, no .bmp is shown, just a weird symbol, sometimes some sort of envelopy thing, sometimes a v-shaped picture. What is happening? This does not happen all the time, not on a regular basis, and nothing seems to be wrong with the input files. Your help is very much appreciated.