I have been trying to run a DirectRT input file with about 200 trials (in 3 blocks) but the computer freezes and the task list shows Execute DirectRT is not responding. I tried breaking up the file into 3 separate sub-files of 1 block each, and embedded them in a medialab questionnaire file separating each of the files with an instruction item (so that medialab would take control after every block was completed). It worked for the first two blocks but the computer froze again before the third block. Rebooting the computer does not help. I am running DirectRT 2008. Please suggest some solution - this is the first time I am facing this problem.