NetworkErro r: 500 Internal Server Error

[eluser]krishnakumar2k[/eluser]
am having this error "networkErro r: 500 Internal Server Error" how can i debugg it?
my .htaccess file is below

Code:

RewriteEngine on
RewriteCond $1 !^(index\.php|resources|robots\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L,QSA]

error log says

[Thu Oct 21 14:13:26 2010] [error] [client 79.170.40.31] File does not exist: /home/sites/........../public_html/favicon.ico