I reverted the page to the default MinimalEntropy skin and grey-title container, with no effect.  Still no edit menu for Locations.  Hovering the mouse over the Settings menu icon did not produce a URL but I was able to fake the full URL you gave by copying what was in the address bar, pasting it into Notepad2, and editing it to produce the string you suggest.  That brought up the Locations edit dialog and I was able to add a new location, but I have been totally unable to reach the dialog except by this major kludge.  We can work with this by bookmarking the link, but what a mess.

I do know that, of course.  I also know that, after a merger, our new parent organization is building a new web site (in WordPress) which will replace this web site, at some point in the not too distant future.  (I think)  I tried upgrading to the current Events and was told it's incompatible with my version of DNN; I tried upgrading to DNN 7 last summer and ran into multiple problems, including the fact that it apparently doesn't support our commercial theme (or the theme doesn't support it).  Upgrading to a new theme would cost us money I don't want to spend, given the site is going away shortly.  We'll just have to live with it.