I am totally exhausted with the .htaccess file (Joomla core SEF), I tried everything I could and I read lots of related articles from Joomla Forum site, but NONE of them are worked. I do not know what's wrong with it, I hope someone could help me ASAP if possible. Really appreciate!!

I have already wrote a test .htaccess file (according to JoomProsolution.com's testing .htaccess file), and it works. That means mod_rewrite is enable. I have already asked the hosting company, they said the .htaccess override is enable also. The hosting server environment is Apache 1.3.33 (Unix) and PHP 4.4.4, the PHP register_globals is currently on.
The .htaccess file that I tried is following: (Joomla was installed under root directory and domain is like
http://www.mydomain.org)
## Can be commented out if causes errors, see notes above.
Options +FollowSymLinks #I tried commented, uncommented and also none + sign in frond of FollowSymLinks, none of them worked

#
# mod_rewrite in use
RewriteEngine On
php_flag register_globals off #Joomla suggests to turn it off, I also tried php_value register_globals 0, and does not work either
# Uncomment following line if your webserver's URL
# is not directly related to physical file paths.
# Update Your Joomla/MamboDirectory (just / for root)
# RewriteBase /
RewriteCond %{HTTP_HOST} ^mydomain.org #with or without these two lines, are all causeed Internal Server Error message
RewriteRule ^(.*)$ http://www.mydomain.org/$1 [R=301,L]########## Begin - Joomla! core SEF Section
############# Use this section if using ONLY Joomla! core SEF
## ALL (RewriteCond) lines in this section are only required if you actually
## have directories named 'content' or 'component' on your server
## If you do not have directories with these names, comment them out.
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} ^(/component/option,com) [NC,OR] ##optional - see notes##
RewriteCond %{REQUEST_URI} (/|\.htm|\.php|\.html|/[^.]*)$ [NC]
RewriteRule ^(content/|component/) index.php
#
########## End - Joomla! core SEF Section
########## Begin - Rewrite rules to block out some common exploits
## If you experience problems on your site block out the operations listed below
## This attempts to block the most common type of exploit `attempts` to Joomla!
#
# Block out any script trying to set a mosConfig value through the URL
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|\%3D) [OR]
# Block out any script trying to base64_encode crap to send via URL
RewriteCond %{QUERY_STRING} base64_encode.*\(.*\) [OR]
# Block out any script that includes a