I've just done a restore from backup after a problem and the character sets are wrong on some of my application MENUS.

All the English menus are CORRECTLY displayed in ISO-8859-1 (English)
Simplified Chinese Mozilla Firefox menus are correctly displayed in Simplified Chinese
However all the other Simplified Chinese versions of applications have their menus displayed incorrectly with ISO-8859-1 so its all unreadable garbage instead of Chinese.
Within the applications and on the desktop all the filenames are correctly displayed in Simplified Chinese
Also I can SWITCH between English and Pinyin keyboard input by clicking [ch20013] or [ch33521] on the task bar.

I've checked Control Panel -> Regional and Language Options, under the Languages tab, and Install East Asian Languages is already selected.

Anyone got any ideas on what's up?Great news - I noticed what was wrong  

In the "Regional and Language Options" under the Advanced tab it asks for the "Language for non-Unicode programs"
I assumed it meant it wanted the default language, which for me is English - United Kingdom.

What it really means is that for non-Unicode programs such as my Chinese applications, what character encoding should be USED to display menus and dialogs which aren't in English.

As soon as I set this to Chinese PRC, rebooted, and re-installed the applications, everything now DISPLAYS correctly.
That is for Unicode English it displays in English, and non-Unicode Chinese displays in Chinese.

Yippy