Estoy muy confundida (otra vez) con el subjunctivo!

[Flexichick]

Hola a todos -

I'm so confused!

My question is about "dudar" and the subjunctive.

One of my Spanish teachers said that "Dudar + que = subjunctive" while "No dudar + que = indicative". The reasoning is that the first example conveys doubt, while the second conveys certainty.

My new(er) Spanish teacher says that dudar = subjunctive all the time.

I have tried researching this in books and online and found mixed messages.

Can anybody clarify this for me?

Muchas gracias :-)