D620 Bluetooth and Logitech MX1000

I am experiencing an issue with a MX1000 bluetooth mouse, and the integrated BT controllor on my D620. The issue is the mouse responsiveness lags--on first moving the mouse, and especially when I stop movement--the cursor floats past the point it should stop. The issue only started happening on a recent shipment of D620's with the Core 2 Duo processors. The configuration worked flawlessly on my previous D620, with the first-gen duo core processor. This is not just happening on one machine/one mouse; the exact same symptom occurs on three 620's and MX1000's, so we're positive it is not an isolated issue. We've tried installing the latest firmware/software from Dell, with no success, tried ripping off all BT software, and just letting WinXP default drivers do the job, and also tried variation of the Logitech SetPoint software with no sucess.
Was there a change in the BT controllor between these models of D620? Any help would be appreciated, as this issue makes the mouse almost unusable.