500 - unable to handle this request.

Beginning to work on a site that I wanted to create individual module placements; such as videos on side bar etc... Not to certain how to do that since when in modules they won't show individual pages; unless I set them up as a single post in the joomla menu..

Love to have that answered..

But the main reason I am writing is because I created to sidebar 2 videos and when I click within modules to place within the category it is blasting a blank 500 error page not working.. Page breaks, but as soon as I disable sidebar on category it's gone and page works..