Android 2.3 set call volume
I've had a similar problem, sometimes the volume is at max and won't decrease, sometimes the other way around. It also started occurring on CM7.1 (but on a Galaxy S). The volume controls start responding after pressing them both ways (i.e. if volume is at maximum, increase first and then decrease, and vice versa).

You should also check if your phone's version has amplification settings in Settings -&gt; CyanogenMod settings -&gt; Sound or something like that.