UI reverting to English?

[Michael Bauer]

Has anyone else had the experience of Ubuntu (Mubuntu 14.10 
specifically) suddently switching parts of the UI back to English? I 
noticed this recently when downloading and overwriting a file, strings 
which have been localized for a long time ("A file named %s already 
exists. Do you want to replace it?", "Cancel", "Replace" and some 
others, screenshot here http://www.akerbeltz.org/sealach/mubuntu.png).

All the relevant translations are up to date. I'm not prompted for 
missing langpacks when going to Language Support and all my updates are 
installed (apart from that Jave thing which for some reason won't install).

Please don't say 'you can fetch those by using $ sudo 
code-that-makes-my-eyes-water' - that's nice but I'm more concerned 
about end users not plugged in to this mailing list who are using a 
localized version.

Michael