hi tom,
this is my complete .htaccess:

Options +FollowSymLinks
RewriteEngine on

RewriteRule ^admin$ - [L]
RewriteRule ^admin/(.*) - [L]
RewriteRule ^install$ - [L]
RewriteRule ^install/(.*) - [L]
RewriteRule ^$ index.php
RewriteRule ^channel/(.*)?/?(.*)/ channel_detail.php?id=$1
RewriteRule ^view/(.*)/(.*)/ view_video.php?id=$1 [L,QSA]
RewriteRule ^tag/(.*)/(.*) tag.php?search_id=$1&page=$2 [L,QSA]
RewriteRule ^detailed/recent/(.*) video.php?category=recent&page=$1&viewtype=detaile d
RewriteRule ^detailed/viewed/(.*) video.php?category=viewed&page=$1&viewtype=detaile d
RewriteRule ^detailed/discussed/(.*) video.php?category=discussed&page=$1&viewtype=deta iled
RewriteRule ^detailed/favorites/(.*) video.php?category=favorites&page=$1&viewtype=deta iled
RewriteRule ^detailed/rated/(.*) video.php?category=rated&page=$1&viewtype=detailed
RewriteRule ^detailed/featured/(.*) video.php?category=featured&page=$1&viewtype=detai led
RewriteRule ^detailed/random/(.*) video.php?category=random&page=$1&viewtype=detaile d
RewriteRule ^recent/(.*) video.php?category=recent&page=$1
RewriteRule ^viewed/(.*) video.php?category=viewed&page=$1
RewriteRule ^discussed/(.*) video.php?category=discussed&page=$1
RewriteRule ^favorites/(.*) video.php?category=favorites&page=$1
RewriteRule ^rated/(.*) video.php?category=rated&page=$1
RewriteRule ^featured/(.*) video.php?category=featured&page=$1
RewriteRule ^random/(.*) video.php?category=random&page=$1
RewriteRule ^rss/new/ rss.php?type=new [L]
RewriteRule ^rss/comments/ rss.php?type=comments [L]
RewriteRule ^rss/views/ rss.php?type=views [L]
RewriteRule ^group/(.*)/ groups_home.php?urlkey=$1
RewriteRule ^([^/\.]+)/favorites/(.*) user_favorites.php?username=$1&page=$2
RewriteRule ^([^/\.]+)/playlist/(.*) playlist.php?username=$1&page=$2
RewriteRule ^([^/\.]+)/friends/(.*) user_friends.php?username=$1&page=$2
RewriteRule ^([^/\.]+)/public/(.*)$ user_videos.php?username=$1&type=public&page=$2
RewriteRule ^([^/\.]+)/private/(.*)$ user_videos.php?username=$1&type=private&page=$2 [L,QSA]
RewriteRule ^([^/\.]+)/groups/(.*)$ user_groups.php?username=$1&page=$2 [L,QSA]
#RewriteRule ^([^/\.]+)?/?$ user.php?username=$1 [L,QSA]
php_value max_input_time 600
php_value max_execution_time 600
php_value post_max_size 50M

as you can see there is a :
#RewriteRule ^([^/\.]+)?/?$ user.php?username=$1 [L,QSA]
That s from my host provider that had to do that cause of this line everytime i was creating a subdomain on the server i was getting a 404 error when tryin to http it.
Any way to fix that bug that this line unfortunately creates to the whole server?anyway to limit it s function to the subdomain where it s uploaded?
best regards
herve