GMap Blocks not displaying

I have two GMap Blocks in a local (XAMPP) installation, one displays properly, the other is only a GBOD (Gray Block of Death). I've installed the GMap Blocks module on several local installations, and messed around with everything I can think of, but so far only one block works. API Key, no API Key, flush cache, ./admin/settings/performance >> Clear cached data ("Block cache: Disabled" so it's a moot step anyway) - nothing seems to work. For the life of me I can't figure out what the problem is. Anyone have any ideas?
See also: attachment.