I would start with your php config file, check what is enabled on your end and what is enabled on the other end. but first check your config file and look for rewrite short open tags switch it to true. these are very basic but you didn't give a whole lot of information, maybe post a few lines of code before and after 172 let me see what is going on there. also if you are using htaccess files and are still using the default CI example i would switch it to this works like a charm: this is a universal htaccess file no matter your setup you dont have to change it promise you that the best thing since sliced bread.
# Customized error messages.
ErrorDocument 404 /index.php
# Set the default handler.
DirectoryIndex index.php
# Various rewrite rules.
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L,QSA]
</IfModule>
i am going to be on for a while if you reply maybe we can get this worked out for you two heads are better than one thing you know