The 1477 number indicates that there is a data corruption. Data corruption happens for any number of reasons. There could be a bad network cable, a PC could have been shut off while the Youth Assistant is running, a PC could have lost network connection, etc. There isn't anything that you have done to cause this to happen. 

If you have a backup file it is best to restore a backup file. If you do not have a backup file then contact our support staff and they will give you further details about getting your data file fixed up.