Randomly skipping trials??

I've got an input file I've created where trials in Block 3 (basically the entire experiment) are being skipped over completely. Within Block 3 I've got the trials randomized--the other blocks where I'm not randomizing are running fine. I've run 9 subjects and do not have the same number of trials for any of them when I go back and look at the output files. The missing trials seem to be random--its not the same trial # missing every time, and it's happening across multiple (4) computers. I'm using an older version of DirectRT (Version 2004.1.0.42), so I'm not sure if that's influencing anything.

I've attached a subset of the input file--any ideas on why this might be happening??? Thanks for your help!!

This subset of trials looks fine. Do you get the problem if you run just this subset? If so, could I see the data log file that is produced?