How do i make my amp stop producing static like sound everytime i connect my guitar ?

I have marshal MG10 kerry king edition , and everytime i connect my guitar a static like sound is produced from the amp ,when i touch the strings the sound stops once i let go it starts again ,it sounds like static ,its making a hole in my head and i cant play well because the sound ruins the melody ,is there a way to fix this , or to stop that sound without having me to put my hand of the strings 24/7 ??? BTW the problem only happens when the amp is on overdrive ,when its clean no static sound ,and the floor the amp is on is wood so i dont think its a problem of the surrounding