Re-downloading 400MB multiple times?

[:1]The other day I opened steam and noticed it was downloading a ~500MB update for SC2. I thought, "Awesome, there's a patch", but when I went to play it, it was still v1.14.
Now, I was just in a game when SC2 froze (not sure why, has never happened before). Looking at steam, i see it is once again downloading a ~500MB update. If I try to launch SC2 from within steam, it doesn't let me (comes up with the progress bar), but launching it from a shortcut works (I think the crash may have been caused by steam writing to a file while in game).
From this I guess that the crash was a symptom rather than the cause (before the first update there was no crash), but it looks like something is corrupting the files causing steam to re-download.
The following two files were updated:
gamedata/loc_US.scd (138KB)
sounds/win/fmod/SC2_VOB.fsb (484,314KB)|||Let Steam verify the integrity of the game cache.|||Spooky|||I am guessing that you somehow toggled the German language version of the game in Steam, which requires a completely separate voice file be downloaded, then toggled it back to English, which triggered another download to replace the original files.
- Servo|||GPG-Servo|||The depot system that the Steam installer uses seems to prefer file replace over file rename, so the files are handled as if they were identical to the english version.
This does mean that once a person selects their language, they normally have ~500Mb less download to endure, the drawback would be for anyone who switches languages post-install. I don't know why anyone would do that on a regular basis, but if there is a good reason, I would suggest manually renaming the voice file (by default) C:\Program Files\Steam\steamapps\common\supreme commander 2\sounds\win\fmod\SC2_VO.fsb between different language sessions.
As to how you triggered a language switch, I know there are at least two places in the Steam interface where you can switch language, but I don't know how you could trigger it by accident. This is the first incident I have heard.
- Servo