I have the following set of controls.

Scenario 1:

If you select one of the first 3 radio buttons and click enter, focus will jump to the Passport Number text box. If the user selects "Other", the "Other, Please Specify" textbox is enabled and, for convenience, screen focus (the cursor is moved) to that textbox.

Scenario 2:

The "specify Other" text box is hidden until the user clicks on the Other Radio button. Upon doing so, the textbox is made visible and the cursor is placed in this textbox.

Which scenario do you feel is a better approach? Perhaps you have another variation? Please state your reasoning.

I would also appreciate it if you could make a generalized statement as to when hiding is better than disabling or vice versa, but I am also interested in this particular example.

Thanks.

Afetrthought: Perhaps, in the 2nd example, the "Please Specify" text would only appear after the user has selected the 'Other' radio button.