BBB cpu frequency problem

Hi, I have a BBB which runs on Android. I was using it without a problem on 1 GHz . But suddenly it stoped working on 1GHz and it’s been working on 800Mhz. I didn’t change anything in kernel or in hardware. I’ve just installed and unistalled some apps. I’m using adb to see cpu frequency:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

It returns 800000. And

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

returns 300000 600000 720000 800000

Before this problem, it was returning 1000000 too. I’m using 5 V DC not usb. In Angstrom It still runs on 1 GHz. What could be causing this problem in Android??