Home, Back, Menu, Search buttons not working Suddenly, Home, Back, Menu, Search buttons are not working.  No amount of rebooting or taking out the battery work.

I saw somewhere that clearing the Dalvik cache might work, but I got as far as getting adb running, only to discover I need root access to clear the Dalvik cache.
This means the provisioning (first run) got somehow interrupted.

To fix this, run the following command from a root terminal or from adb shell:

sqlite3 /data/data/com.android.providers.settings/databases/settings.db "INSERT INTO secure (name,value) VALUES ('device_provisioned','1');"

and then reboot.