Well...These annoying things happen all the time...
1.If, for some reasons(like play games of some non-unicode), you have to switch your default internal language code of your system, I recomment you to use Microsoft Applocale. This tool helps you to change the internal code without restart your computer. But here comes the thing: the tool has some bug that it will infect Windows Installer! And the result is if you wanna set up a program with Windows Installer, words in the set-up process will transform into unrecognizable shapes~ To fix this, open C:\WINDOWS\AppPatch\Apploc.tmp with "notebook", delete everything in it and save. Then change the attribute of this file into "Read only". Done!
2.Some thing happens, and then your key settings of your IME input program get into a mess. There is no way you can set them back using the "key setting" button in Text Service and Input Languages. Try it yourself and you'll see. But there is a quick way to restore the original settings. Delete C:\Documents and Settings\USERNAME\Application Data\Microsoft\IME\MSSCIPY\PUSERNAMESx.DAT and everything is back!
NOTICE: The red part is changeable according to your own username.
Oops, it is easier to say than to research. Some applause please~