I created a page and named it About Us and when I go to the home page (which is the name of the page) and then go to the Href and get this
About%20Us

I view it and I get file not found

I go the the About us page and put in "Home" in the Href and view again and the same thing happens. I do not get the %# in this box.

The problem there is you have spaces in your file name which is a big no-no! That is what the %20 is.

To fix this, go into Manage Project and rename that page to just about us (all lower case and no spaces). Then in the Href box for the element you want to link, just start typing the page name and it will select the aboutus page.