This issue should be fixed as of v3.8.0 – if you haven’t updated yet now it’s a good time to do it. Note that a full uninstall/reinstall of both JuiceDefender free and Plus/Ultimate is necessary.

It had been reported notably on some Sony models and the LG Optimus V, but other devices might be affected.

The cause is a rather poor implementation of their “differentiating” customized launchers by the manufacturers. JuiceDefender uses one particular API call, which is admittedly rarely used, but part of the standard API nonetheless. It seems that Google forgot to insert that specific case into their Android compatibility test suite…

If you’re still experiencing this problem with v3.8.0, please help! See this thread in the development forum. The workaround will be extended to all affected devices as soon as enough feedback is gathered.