3 users same PARADOX database on peer to peer network

I use a paradox database ref.DB who is on PC4.
The clients are PC1, PC2 and PC3 and connected in a peer to peer network
The netdirparh  is \\PC4\c for all the 3 clients
Local share is TRUE by all clients.

The problem is that I must startup the programs in the
sequence PC1, PC2, PC3.
f.e. when I first start the program on PC2, then PC1 gets the error-
message 'Active directory not Found'
If I shut down the programm, start first PC1 and then PC2, .. everything
works fine.
What am I doing wrong ???

I have allready read
but there is no solution for my problem. I simple want that every PC can
the ref.DB database anyway , independent which program must start first.
Has someone have the same trouble ?

Thanks for helping me!