Not sure what's causing it. But sounds you have some good backups and it might be a good time to do some work in the Project Utilities section. Check/Repair and Pack. Packing reduces the total disk space used and also rebulds all index files associated with a project. Make sure to read the info in your manual or in the help section of UFT about that. Never hurts to use these utilities on a regular basis, especially after entering a lot of new data.