[squid-users] Strange cache.log Entries

The following entries appeared in the parent cache's cache.log file.

        2005/04/21 03:09:20| NETDB state saved; 0 entries, 14 msec
        2005/04/21 03:11:09| Failure Ratio at 1.09
        2005/04/21 03:11:09| Going into hit-only-mode for 5 minutes...
        2005/04/21 03:16:13| Failure Ratio at 1.05
        2005/04/21 03:16:13| Going into hit-only-mode for 5 minutes...
        2005/04/21 03:21:14| Failure Ratio at 1.06
        2005/04/21 03:21:14| Going into hit-only-mode for 5 minutes...
        2005/04/21 03:26:14| Failure Ratio at 1.09
        2005/04/21 03:26:14| Going into hit-only-mode for 5 minutes...
        2005/04/21 03:31:16| Failure Ratio at 1.05
        2005/04/21 03:31:16| Going into hit-only-mode for 5 minutes...
        2005/04/21 03:36:16| Failure Ratio at 1.05
        2005/04/21 03:36:16| Going into hit-only-mode for 5 minutes...

The above is an excerpt from the file but has been occuring all week long.
I've never seen either of the entries in the past.

What would trigger this condition?

Merton Campbell Crockett

-- 
BEGIN:				vcard
VERSION:			3.0
FN:				Merton Campbell Crockett
ORG:				General Dynamics Advanced Information Systems;
				Intelligence and Exploitation Systems
N:				Crockett;Merton;Campbell
EMAIL;TYPE=internet:		mcc@CATO.GD-AIS.COM
TEL;TYPE=work,voice,msg,pref:	+1(805)497-5045
TEL;TYPE=work,fax:		+1(805)497-5050
TEL;TYPE=cell,voice,msg:	+1(805)377-6762
END:				vcard