Crazy Stuff With URLS

I have a site and for some reason the url structure does not work correct.

example of problems
this would be the correct url : storename.com/category/subcategory/product

it displays incorrect if you put in : storename.com/subcategory it shows storename.com/category/subcategory/

It seems like after the storename.com/ it dont matter what you put as long as the end / is something on the site it will go to that page.

I hope this made sense any help on this matter would be great.

Thanks

... to me, it does not.
Why not just post an url, this would make sense.
Ernie