As always, thanks for your response.
I have not changed strings yet (the set is now 2 months) but I'll do this week.
I have gently tapped the saddles just in case.
I'm starting to think it's more a Windows Vista equalizer issue.
I`ll test it by tomorrow (if my dentist let me alive) evening with a ZoomH2 recorder.
I'll keep you informed.
Again, many thanks.