Cannot delete dns root zone (.) windows server 2003 r2

Dear Sirs/madams

I have a domain with 3 dcs/dns: 2 X server 2003 r2 and 1 X 2008 r2.all of them face the error "The DNS server encountered error 9002 attempting to load zone . from Active Directory. The DNS server will attempt to load this zone again on the next timeout cycle. This can be caused by high Active Directory load and may be a transient condition.

All of them have root hint servers so from what I read i dont need root zone so I want to delete it but: 1)under dns console there is no . zone 2) from users&computers console there is no .zone neither 3) from command prompt running dnscmd /enumzones I can find a zone

".       Cache      AD-Domain"

how I can remove it from all dns?

Regards ,

Miltos