If I understand you correctly, the DVD does at least start the installer and quits only after a bit into the installation and it's not your DVD that is physically damaged. Some people who had to remove Fortius software first were successful by unistalling .net 1.1, see http://forum.tacx.com/viewtopic.php?t=1 ... 48bec49764
I had the same error and got rid of it by uninstalling .NET 1.1, enabling .NET 3.5 in Win 7, and by following mcorn's advice and installing ffdshow 64 bit, installing DirectX, Visual C++ and XMA directly from Microsoft's download center prior to the then successful attempt to install TTS2. Not to forget updating everything that could be updated, from BIOS to audio and video drivers. After installing TTS2, I removed ffdshow again. So I cannot tell which single action was responsible for success. But I happily cycle on my Fortius now under TTS2, while the weather outside is cold and grey and ugh.. Good luck!