I'm having the exact same problem here; EA Servers connect fine, I can play multiplayer, but Galaxy at War Map gives me a 'failed to load' report. Briefly, a couple days ago, it worked, but since then - zilch.
I cannot agree more strongly with a player who says that SP and MP should never be connected! (That should probably be posted in a Bioware forum), but 100 percent on the money. ME3 has, in someways, destroyed what was so great about ME1 an ME2 - ending aside.. having this many technical issues is awful.
I really hope EA is paying attention - if you even want a chance for ME4 to succeed - don't pull the end of ME3; look really hard at what - especially ME 1 - made ME1 and ME2 work, don't mix SP and MP, or force us to be connected to the Internet to PLAY the game; 1 time authentication on initial install is okay, but not this persistent crap - i.e. if the internet doesn't work we can't play the game we spent our hard earned money on; and finally - if you do have MP - make sure your servers are functional.
A long time ago EA was an awesome company - I remember playing some early EA games in the early 90s; Bioware was an excellent company and should be a good asset, but please don't think all quick profit and turn out something less than what it could be.
This extended replay is courtesy due to te link posted by an EA representive which yielded "Oops, an Error has Occured" message. That is how bad the tech end seems to be. I'd be laughing if this didn't mess up the game so much.