Why it can get corrupted:
1. Current hand2note version does not work well with such large databases , hopefully will be fixed in Hand2Note 4, there will be implemented a bit different database structure. And it should be more optimized overall.
2. Turning off your PC without closing Hand2note. You need to close Hand2Note manually before turning off your PC or restarting it. So that database can save everything.
3. Electricity loss power loss, basically the same as #2
4. Usage of external hard drive for DB storage
We do not recommend to keep such large databases for playing.
In case if you are using different databases with different settings/huds/game types for Range Research and playing. You can copy and clone whole Hand2note folder and then you can use Hand2Note1 for playing, Hand2Note2 for range research, you will not have to switch any settings/huds/databases. Just launch the icon from the folder that you want to use.