What is clear from the play is that as the action of the play progresses Macbeth alienates more and more of his Lords through his tyranny. The first hint of dissent we can identify is in Act II scene 4, where, depending on how you play it, Macduff clearly suspects Macbeth of having an involvement in the regicide of Duncan and refuses to go to his coronation. Act III scene 4, with the appearing of Banquo's "ghost", clearly would unsettle those supporting Macbeth, and likewise in Act III scene 6 we see strongly veiled hints that Lenox is suspecting Macbeth as well, as he identifies that under Macbeth, Scotland is suffering:
Some holy Angel
Fly to the court of England, and unfold
His message ere he come, that a swift blessing
May soon return to this our suffering country
Under a hand accurs'd!
Act IV scene 2 features one of Macbeth's most notorious desperate acts, when he organises the slaughter of Macduff's wife and children - poignantly shown on stage (in comparison to Duncan's murder which was off stage) to exacerbate the severity of the crime. Note how the dialogue between Lady Macduff and her son really endears them to us before their slaughter.
Then in Act IV scene 3, Rosse describes Scotland under Macbeth:
Alas, poor country!
Almost afraid to know itself. It cannot
Be call'd our mother, but our grave; where nothing,
But who knows nothing, is once seen to smile;
Where sighs, and groans, and shrieks that rent the air
Are made, not mark'd; where violent sorrow seems
A modern ecstasy: the dead man's knell
Is there scarce ask'd for who...
Clearly the effects of Macbeth's rule are detrimental, as recognised by a number of characters. In Act V scene 3, we are presented with a resolute Macbeth, who says:
Bring me nor more reports; let them fly all
Obviously a number of lords and soldiers have been defecting from him as a result of his despotism but also the oncoming invasion. The Polanski version of the film pictures this desertion wonderfully with Macbeth being left alone to defend his castle, "safe" in the knowledge that none of woman born can slay him.