named fails answering

[Radu "Ux" D.]

Hi

I have a named 9.3.1 running just fine on Windows. The resolution is 
working ok.
The named is restarted (through service stop / start) just fine. 
Sometimes, after that:
- named takes 26% of CPU
- any resolution time outs
- rndc run against it on local machine hangs
all that until named is restarted again. After restart, everything is fine.

How can I continue to debug the issue?

Thx, Radu
p.s. the named.conf is simple like

controls {
    inet 127.0.0.1 allow {any;} keys {_nbc_command_channel_key_only_;};
};
options {
    directory "__________________";

    check-names master ignore;
    check-names slave ignore;
    check-names response ignore;
};
logging {
    category notify { null; };
    category lame-servers { null; };
    category update { null; };
};
zone "1.0.10.in-addr.arpa" in {
type master;
file "1.0.10.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "1.10.in-addr.arpa" in {
type master;
file "1.10.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "128.37.170.in-addr.arpa" in {
type master;
file "128.37.170.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "130.130.in-addr.arpa" in {
type master;
file "130.130.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "14.37.170.in-addr.arpa" in {
type master;
file "14.37.170.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "16.10.in-addr.arpa" in {
type master;
file "16.10.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "17.10.in-addr.arpa" in {
type master;
file "17.10.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "242.37.170.in-addr.arpa" in {
type master;
file "242.37.170.in-addr.arpa.db";
    update-policy {
    grant _nbc_update_channel_key_only_ wildcard * ANY;
    };
};
zone "." in {
type hint;
file "root.cache.db";
};