HowTo turnoff Apache2 cache on Ubuntu

Here is my problem: after default installation of apache2 for Ubuntu it's started to retrieve old pages for Trac, for example, I made a small changes (simply edit page) in trac-wiki section, push "Submit" button, and after the page updated I saw a page with new changes, but when I click on "Edit" button again on the same page, it gave me the edit page without the last changes (cache gave me back the old page – and I have to press F5 to update the page)…

PS: when I configured HTTPS on my server, the problem for HTTPS content disappeared!

Here is what I'm using:

1. System: Linux hostname 2.6.32-24-generic #39-Ubuntu SMP Wed Jul 28 05:14:15 UTC 2010 x86_64 GNU/Linux
2. Trac 0.12
3. Python 2.6.5
4. Apache 2:

$ apache2 -V
Server version: Apache/2.2.14 (Ubuntu)
Server built:   Apr 13 2010 20:22:19
Server's Module Magic Number: 20051115:23
Server loaded:  APR 1.3.8, APR-Util 1.3.9
Compiled using: APR 1.3.8, APR-Util 1.3.9
Architecture:   64-bit
Server MPM:     Worker
  threaded:     yes (fixed thread count)
    forked:     yes (variable process count)
Server compiled with....
 -D APACHE_MPM_DIR="server/mpm/worker"
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
 -D APR_USE_SYSVSEM_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=128
 -D HTTPD_ROOT=""
 -D SUEXEC_BIN="/usr/lib/apache2/suexec"
 -D DEFAULT_PIDLOG="/var/run/apache2.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_ERRORLOG="logs/error_log"
 -D AP_TYPES_CONFIG_FILE="/etc/apache2/mime.types"
 -D SERVER_CONFIG_FILE="/etc/apache2/apache2.conf"

Thanks for advice!

PSS: If you need some more outputs of some configures, just comment me, and I append them to my question post!