Double index.php: Next/Previous Links Problem

My problem is that the next and previous links don’t work on my blog: http://games.iflove.com/

When I point to the Previous Entries, it shows the address http://games.iflove.com/index.php/Index.php/page/2/

See here it has two “index.php” in this link. That is an invalid address. The right address should be http://games.iflove.com/index.php/page/2/

Why it gives double “index.php” in the Previous Entries???

The URL displayed in the address bar is correct, e.g. http://games.iflove.com/index.php/page/2/, but only the front page of my blog is shown. I am using next_posts_link and previous_posts_link.

Could anyone point me in the right direction for how to get this working, I would be appreciate it very much.