I have been having the same issue. I was using an earlier version and tried to upgrade to 2.0 and now it will not run at all. I have uninstalled all the app data, cleared the registry, tried both 32 bit and 64 and neither have worked. I can't even get past the screen with the checkbox for the terms before a windows error pops up stating Bittorrent Sync has stopped. The only other step that I can think of would be to do a clean install of Windows and start from scratch, but I really do not want to do that. It is working fine on one machine, but the other one that I need to sync with will not run at all.