I've watched and read a couple of guides on how to mute unwanted noise, but they don't seem to be covering on what my problem is.
So, my problem is when I am playing palm muted notes (with distortion), and I move onto a different fret with my index finger, the lower part of that finger presses onto the higher strings, sounding like i am playing a horrible hammer on with the lower part of my finger.

For example: http://puu.sh/j9xMh/a44145bed2.png (Copy and pasting the ascii tab somehow messes up. Tab from here: http://tabs.ultimate-guitar.com/s/system_of_a_down/question_ver2_tab.htm)
In the above example, all of those notes are played in palm mutes. So at the 9th fret, my middle finger is playing that, but as I play the 7th fret when I press down with my index finger, the lower part of my finger would press against the higher a and c strings, producing a short ugly sound.
What's a good technique on how to prevent that?


If im not too specific enough, please let me know.
Does the ugly sound come when you pluck or just when you press down with your finger
I would try just using the fret hand without plucking any strings.
sound out the notes that way until you can get it without the errors