I came across a stange behaviour from one of my favorite Les Paul rig , I've uploaded it today to Rig ex for analysing
" Marshall jtm 30 2x10LP2 "
I get a strange bass warble just like an octaver on E chords ( with hard attack ) - It's even worst while de-activating the Cab Sim
It's ok with LCF Off 
Same pb with strat or LesPAul
Is there Anyone with same pb than me on this rig ?