cache not cacheing

I have a cache server that I can't get to cache.

It stores pages and when a new request arrives it throws away the old page and
gets a new one. It seems to incorrectly deciding that the page is stale.
Looking through my log files I see almost all the entries are TCP_REFRESH_MISS
entries. However the cache works fine with pages that contain explicit expirery
information.

I turned on debug and inspected the refresh check:
97/08/15 09:10:33| refreshCheck: Matched '. 0 100% 604800'
97/08/15 09:10:33| refreshCheck: age = 67
97/08/15 09:10:33| refreshCheck: YES: lastvalid <= lastmod

Curious as to why 'lastvalid <= lastmod' I added some more debug and got:
97/08/15 17:15:44| refreshCheck: Matched '. 0 100% 604800'
97/08/15 17:15:44| refreshCheck: age = 82
97/08/15 17:15:44| refreshCheck: YES: lastvalid (871629262) <= lastmod
(87162926
2)

The lastvalid and lastmod variables are the same. So it seems that squid is
failing to get last modified information and instead clones the timestamp.

Given that the squid refresh algorithm depends on last modified information, I
seem to be in trouble.

I upgraded squid to the latest stable version (1.1.14) and no change.

Any help or suggestions would be very welcome since I have run out of ideas.

-- 
Daniel Harrison				Ph. (02) 9351 5519
Network Administrator			D.Harrison@isu.usyd.edu.au.
Sydney University			Bld H08, Sydney
Confidence is the feeling you have before you understand the situation.