Database Corruption

I have a database with about 90 tables
In some occasions when I use Set Relation To, the child table doesn't move with the parent table.

I have reindexed many times all tables. Also I have used VALIDATE DATABASE RECOVER wit out solving the problem.

If I free a child table from the database, it's works correctly, but When I put the table inside the database it doesn't work again.

I'm using VFP 6.0 with Novell 4.11 and I'm using Fox since FoxBase and it's the first time I have this kind of problem

Thanks in advance

Carlos Restrepo