David, you have a real version mix here. I just tried running it here on my Windows 7 machine using 2010.125.831.10, built on August 31st, 2010. Ran through nicely. This version is actually the first official (non-beta) release of DirectRT 2010 which we have not yet posted publicly (but will this week). If you email John via sales@ he can get you the link and the code if you would like to install that on one of your machines that has the issue and see if that resolves it. We have been gradually distributing this release since the beginning of September to test its reliability and we have had very few reports of bugs/issues of any sort. No guarantee, but that's where I would start first.