Print dialog of Excel.Interop freezes

Question

Here's my function that I use to show print dialog (I write on C#). It was working nicely, when i wrote it. The problem is - since some day this code keeps only freezing my app instead of any printing. I tried also Show() with all 30 Missing params, but it doesn't make any change.

public bool Print()
    {
        var f1 = _application.Dialogs;
        var f2 = f1[Excel.XlBuiltInDialog.xlDialogPrint];
        bool DidntCancel = f2.Show();
        return DidntCancel;
    }

Freezing happens in f2.Show() call. My app window keeps refreshing it's view, but I can't click on anything. A tried to go into Show() method assembler lines via ste-by-step debug, but program doesn't go there, it dies exactly on the moment of method call. Any help is very appreciated :)