squid显示的网页是过期的，怎么办？

antelope

今天发现，我的squid显示的网页明显是旧的网页，可能是几天前浏览同一个网页时存下来的，按ie刷新按钮，可以更新为新的网页
请帮忙解决！

以下是squid的配置文件
http_port 3333
httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on

#
half_closed_clients off
cache_swap_high 100%
cache_swap_low 80%

#
#icp_port 0
#
cache_mem 96 MB
maximum_object_size 4096 KB
cache_dir ufs /usr/local/squid/cache 6000 16 256
cache_access_log /var/log/squid/access.log
cache_log /var/log/squid/cache.log

#user&group
cache_effective_user squid
cache_effective_group squid

#
visible_hostname star.mobspace.com

pid_filename /var/run/squid.pid
dns_nameservers 192.168.1.1

acl starpointcomm src 192.168.1.0/24
acl all src 0.0.0.0/0
http_access allow starpointcomm
http_access deny all