Are you using Windows 8.1? We have discovered a problem with upgrades from Windows 8.0 to 8.1. NVivo opens without error and allows you to navigate around the programme but any attempt to open a node results in the node displaying as empty and then the software freezes. The good news is your data is safe as we have already checked this by opening the same project on other computers not running W8.1. The bad news is that the developers of NVivo, QSR, are looking into this problem but have not come back to us with  a solution as of today. I'll keep you posted on developments as this bug will be sorted out quite quickly because it is so serious for users who effectively, can't use the software until this issue is addressed.