Forum 500 Internal Server error when deleting threads or posts

[محروم.كوم]

I get a 500 Internal Server error when deleting threads or posts. The logs state:

[Sun Sep 12 20:23:05 2010] [error] [client ] mod_rewrite: maximum number of internal redirects reached. Assuming configuration error. Use 'RewriteOptions MaxRedirects' to increase the limit if neccessary., referer: http://www.xxxxxx.com/forums/postings.php [Sun Sep 12 20:23:05 2010] [error] [client ] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://www.xxxxxxx.com/forums/postings.php Here are the contents of my .htaccess

Code:
RewriteCond %{REQUEST_FILENAME} -s [OR] RewriteCond %{REQUEST_FILENAME} -l [OR] RewriteCond %{REQUEST_FILENAME} -d RewriteRule ^.*$ - [NC,L] # Forum RewriteRule ^threads/.* showthread.php [QSA] RewriteRule ^forums/.* forumdisplay.php [QSA] RewriteRule ^members/.* member.php [QSA] RewriteRule ^blogs/.* blog.php [QSA] ReWriteRule ^entries/.* entry.php [QSA] RewriteCond %{REQUEST_FILENAME} -s [OR] RewriteCond %{REQUEST_FILENAME} -l [OR] RewriteCond %{REQUEST_FILENAME} -d RewriteRule ^.*$ - [NC,L] # MVC RewriteRule ^(?.*?)(?:/|$))(.*|$)$ $1.php?r=$2 [QSA]
Any ideas on where to start? My host was confuesed about the last line in the .htaccess. What is the RewriteRule ^(?.*?)(?:/|$))(.*|$)$ $1.php?r=$2 [QSA] used for and what will happen if it is deleted? __DEFINE_LIKE_SHARE__