i have exactly the same issue as you. i have overclocked my fone a week ago. i changed clock limits by loading lv profile with limits as 250 850. that day it really worked smooth and nice. however from next day onwards it began to lag and started random freezing again so i checked the kernel-config settings and i noticed that it had changed the limits from 250-850 to 125-850.

I have reset the limits back to 250-850 three times so far but later when i check the lower limits change back from 250 to 125 all by itself. i have no idea how to stop it from changing and hope these techies can help us.