Lost password problems

Hello there, I am having issues with our “Lost Password” function, if somebody enters their username and or email address so they can retrieve their lost password after they hit submit it goes to a page not found. Now we had a similar issue with registration, after somebody would enter all of their info and click submit it would go to a page not found, this was solved with changing the forum slug (forums>options>global) which i changed simply to “forum”. So I was thinking it was the same type of issue, any ideas? Thanks for your time. Kevin