Squealing noise while driving, only stops when car is

[2.volvo]

Hello all,
I have a 1999 S70 with 90K+ miles. Just yesterday ( 82 degrees, low humidity) I noticed a squealing/whistling noise coming from outside the car. It's only noticeable when driving with the windows opened at lower speeds- 40mph- due to wind noise.

The squeal starts once the car begins to move and continues at a consistent rate/pitch regardless of speed. The squeal only stops when at a complete halt. Breaking or acceleration does not seem to influence the noise.

I can't say if it happens all the time or intermittently since it's only just begun. I think it happens most often when the car is already warm, and not first thing in the morning when air temps are @ 65 or so.

I am not using A/C or heat.

Any hints to this mystery?

[dvs7310]

This sounds like the same exact problem I'm having, any luck figuring it out yet?

Thanks

[pfeener]

Does the sound vary when turning? Does it disappear or change pitch when cornering at 20 - 30 MPH?