The ondemand or interactive governor switches the cpu frequence. Additional to the frequency, the voltage is changed too, which may be problematic.
This file may be new, you have to create it (exactly "/etc/default/cpufrequtils"). It' read in /etc/init.d/cpufrequtils:
ENABLE="true"
GOVERNOR="interactive"
MAX_SPEED="1010000"
MIN_SPEED="480000"
...
if [ -f /etc/default/cpufrequtils ] ; then
. /etc/default/cpufrequtils
fi
You may also restart only this service-script, probably.