Subject Broken databases

I use firebird for my product and for some times my databases start break.
I read a lot of forums about protection of my databases, but I don't understand what the reason of breaking.
DataBase is broken and can't be restored from backup, but I can work with database and I can repait it(I need about 3 hours for repairing, because I need to recreate all indexes and foreign key and delete phantom records). Repaired database became droken for sometimes. 

I don't understab reasons for broken. Can you help me to find the solution of this problem? 

Maybe I must to show some log's or to turn on some logs that can help to fin solution?