I have been running the same (most recent) 2008 version of MediaLab on PCs that have Windows 7. In most cases, the experiment freezes at the same spot, although a few participants have managed to finish the study without this happening. I read elsewhere on this message board that people were having similar problems with MediaLab running on Vista, so I am thinking of trying their solution of breaking the experiment into 2 smaller experiments as a temporary solution. I'll let you know if this works. If this or another solution works for you, it would be great if you would let me know.