Trackpad scroll/drag still active after I let up

I have an E6520. Great laptop, but I have a problem with the trackpad.

On all other trackpads, if I scroll or drag, the scrolling and dragging stop as soon as I lift my fingers from the trackpad. (Scroll = slide two fingers up/down/left/right, and drag = double click on title bar, but don't let up after the 2nd click, enabling you to move the window around.)

On this E6520, the scrolling and dragging stay active for about 1 second unless I single-click.

For example, if I put the pointer over a title bar, do the double-click-to-drag (where you stay depressed on the 2nd click), then move the window around, then let up, then quickly put my finger on the trackpad again and start moving:

• What should happen: Just the mouse cursor moves.
• What actually happens: The dragging is still active, so the window keeps moving.

The drag won't stop unless I wait about 1 second or click somewhere else.

Same thing happens with scrolling a lot of the time--the scrolling won't stop unless I single click or stay off the trackpad for about 1 second. Sometimes I have no problem.

I even wiped and reinstalled Windows 7 x64 from scratch, installing all Dell-recommended drivers, and I still have this problem.

I am on the A12 BIOS, but I doubt that makes a difference.

This problem doesn't happen with the pointing stick or an external mouse.

Has anyone else run into this?