PhpBB/fetch all doing a funny on me

OK i’ve installed a mod for PhpBB which fetches me posts from a certain forum. But for some reason or other, when the ‘comments’ section for a post is clicked, it brings up an address like -

http://url/forum/comments

instead of

http://mywebsite.com/forum/comments.

It fetches the forum posts fine, but when i try to click comments or echo an icon, it does the above.

Whats even more baffling is that it only does this in IE, not mozilla.

Anyone had this sort of prob before??