First, there are 2 db files in your diablo III folder.
Agent.db which is hidden and
launcher.db (not the diablo 3 launcher-this was my mistake)
-----> use the sort by type function to make them easier to locate
Open both files with notepad
change EVERY occurance of ensg to enus. My launcher.db only said "enSG" and nothing else.
The agent.db had quite a few, i double chedk to make sure i had them all.
Once that is done go to C:\Programdata and delete the battle.net folder
If you want to save yourself 2.6gb of downloading then read here and do what he says.
If you have never used regedit its surprisingly simple if you follow his instructions. To find it just search "regedit" in your programs bar.
All this does is change the language packs to US so diablo doesnt try to redownload them.