IF THERE IS one thing that a road warrior needs more than anything else - more than a limitless expense account; more than a big fat bonus for clocking all those hard miles; more,even, than non-wrinkle, non-stain shirts - it is a road companion. Just a soothing voice to say, "I've got your back; I'm here for you."

That's all.

As for me, I thought I had that companion.

Turns out I was wrong.

Her name? Not important. Things happen. I have my version; she has hers. I respect that.

What I will say is that when we met, I thought she was perfect.

Helpful. Cheerful. She didn't talk a lot, but when she did, it meant something.

I listened.

Not only did I listen, but I also did what she said, and I was rewarded: She rarely steered me wrong.

Now?

Her voice grates.

We're in the car together, and she is sometimes snippy, sometimes coldly silent.

At times, I even wonder why I take her along on these trips.

But I do.

Somehow, I think I still need her.

"In one-tenth of a mile," she says, "at LivingstonStreet, turn left."

At Livingston Street, I turn left.

And she is right. It is the thing to do.

She is almost always right.

Almost always.

And therein lies the problem.

Sometimes she's not.

Maybe it is my high expectations of her.Maybe it is the way she is hardwired to convey an air of infallibility. Whatever it is, when she is wrong, or simply uncertain, things get testy.