Found on 07-10-05-branch on WinMe-Ja. Steps: 1) Create a new ja profile, or change an existing profile to ja language. 2) Start, or relaunch browser (depending on method in (1)). UI in not in Japanese. This was tested by using the lang pack available in latest Win JA branch build.

Just confirmed that I cannot change to DE or JA UI via the View Menu or Prefs in 07-10-05-branch. Could this have something to do with the fix for bug 88630?

Just checked 07-09-05-branch; I was able to change to Ja UI using View menu.

This is the expected behavior. Seamonkey builds dated after 2001-07-09 will *NOT* work with any langpack created before 2001-07-10. Their locale version # doesn't match.

Using a tweak to "update" the localeVersion of the JA pack, I was able to change to JA UI in the 07-10 branch build. I will mark this as verified and reopen if the reported problem happens when the new JA pack becomes available. Bug 90424 has been updated to look into the best way of preventing the installation of incompatible packs.