I have seen the javascript error if you are logged in as Host or Admin and navigate to the child portal using the sub-directory like you described. It is due to the admin menu looking for the javascript popup function in the SnapsisDNN.js file, which is referenced relative to the main root of the website. It can be fixed by making the reference physical from the root of the website by placing a slash at the start of the reference.
On line 34 of DesktopDefault.aspx change:
src="DesktopModules/SnapsisDNN/SnapsisDNN.js"> to
src="/DesktopModules/SnapsisDNN/SnapsisDNN.js"> |