I have always had this problem, but up until now couldn't figure out what caused it, but I have discovered what causes it.
I'm using Cubase 6 on Win XP, using two audio tracks, if you drop a VSL Equalizer into an insert on track 1, and switch ANALYZER on, then all is well, but move the Equaliser to track 2 (by dragging the plug in across), eq still works, but the analyzer stops working (usually), drag the equalizer back to where it was (track 1) and it will start working again. If you use copy instead of move, then it always works OK,
I'm sure there is something wrong here, can anyone confirm this does happen?