LDAP problem ID 8026

LDAP Bind was unsuccessful on directory owens1.owens.local for distinguished name ”. Directory returned error:[0x51] Server Down.

Category : LDAP operations.

We have 2 servers 1 -Dc 2nd Exchnage running on top of 2003 OS.
ID 8026 get logged every few minutes.
I have checked for RUS is pointing to right DC
Next GC settings checked – Dc acts as DC and FSMO roles are enabled on it.
But it still getting logged.
I read somewhere that it may have something to do with DNS forwarders ? Any sugestions ?

I need help, please