404 Page after log-in

My site is up and running, but lately I noticed that once the user log-in they get a 404

"
The requested URL /redred was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

When they hit the back button they are already logged-in. I also noticed that once log-in and you want to view your profile. You get the same 404 page.

Upload.htaccess file and check its working or not

I have re-upload the .htaccess file, but same thing it happens

Here's my .htaccess file


Options +FollowSymLinks
RewriteEngine on

RewriteRule ^admin$ - [L]
RewriteRule ^admin/(.*) - [L]
RewriteRule ^install$ - [L]
RewriteRule ^install/(.*) - [L]
RewriteRule ^$ index.php
RewriteRule ^view/(.*)/(.*)/ view_video.php?id=$1 [L,QSA]
RewriteRule ^tag/(.*)/(.*) tag.php?search_id=$1&page=$2 [L,QSA]
RewriteRule ^channel/(.*)/(.*)/recent/(.*) video.php?category=recent&chid=$1&page=$3
RewriteRule ^channel/(.*)/(.*)/viewed/(.*) video.php?category=viewed&chid=$1&page=$3
RewriteRule ^channel/(.*)/(.*)/ channel_detail.php?id=$1

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/(.*)/members/(.*) group_members.php?urlkey=$1&page=$2
RewriteRule ^group/(.*)/videos/(.*) group_videos.php?urlkey=$1&page=$2
RewriteRule ^group/(.*)/add/(.*) add_video.php?urlkey=$1&page=$2
RewriteRule ^group/(.*)/fav/(.*) add_favour.php?urlkey=$1&page=$2
RewriteRule ^group/(.*)/topic/(.*) group_posts.php?urlkey=$1&tid=$2
RewriteRule ^group/(.*)/invite/ invite_members.php?urlkey=$1 [L,QSA]
RewriteRule ^group/(.*)/ groups_home.php?urlkey=$1 [L,QSA]
RewriteRule ^groups/(.*)/(.*)/(.*) groups.php?chid=$1&page=$3
RewriteRule ^groups/(.*)/(.*) groups.php?category=$1&page=$2
RewriteRule ^include/(.*) http://www.vshare.in
RewriteRule ^pages/(.*).html$ show_page.php?name=$1 [QSA,L]
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]


<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>

<IfModule mod_gzip.c>
mod_gzip_on No
</IfModule>

Make sure that your web host allows .htaccess files.