The Problem
After you migrate your Mac OS from Snow Leopard to Lion, iStat Menu 2 still works fine. But when you do some changes of iStat Menu 2, you will get the following error.
"Could not load extra
iStat menus could not load the disk activity extra"
The Solution
First, go to download the latest MenuCracker.menu from SourceForge and mount the disk image(.dmg).
Then, open "Terminal.app" and run the following commends.
sudo killall SystemUIServer
sudo cp -rp /Volumes/MenuCracker\ 2.2/MenuCracker.menu /Library/Application\ Support/iStat\ local/extras/ (single command)
sudo killall SystemUIServer
Then it will work!
