I am using a Japanese Default Windows 7 Enterprise x64 with the English Language Pack installed. The Region and Language Settings have English as the Display Language with Input Language as Japanese (Japan) - Microsoft IME, Format as Japanese (Japan) and location as Japan for Current User, Welcome Screen and New User Accounts. Installed Keyboard Layouts are English (US), Japanese (Japan) and English (Australia).
When right-clicking on blank space within a folder (and at times on files / folders themselves), the display language for both the right-click menu as well as the display name of all folders and headings automatically changes to Japanese until the folder is closed. If the folder is not closed and the control panel is opened, this also causes certain elements in the control panel to return to Japanese.
An uninstall and re-install of the English Language Pack has not yielded any difference. The problem began a week or so ago and may have been caused by an update, however I would not know which one.
TLDR; How to fix the Windows 7 language display settings to not automatically change context menus and file menus to the default language after a right-click.