sethicles,
Testing the device in your desktop with XP SP3 installed tends to rule out a hardware problem with the drive itself so one should look at the drivers and/or the USB port on the Dell 5160.
Interesting, a search of Microsoft KB says to install the latest service pack to cover the old Upper & Lower Filters and USB detection issues but alas SP3 may not have corrected these problems as MS hoped.

Consider reinstalling all the USB conttrollers on the 5160, here is the steps from MS:
To remove and reinstall all USB controllers, follow these steps:
Click Start, click Run, type sysdm.cpl in the Open box, and then click OK.
Click the Hardware tab.
Click the Device Manager button.
Expand Universal Serial Bus controllers.
Right-click every device under the Universal Serial Bus controllers node, and then click Uninstall to remove them one at a time.
Restart the computer, and then reinstall the USB controllers.
Plug in the removable USB storage device, and then test to make sure that the issue is resolved.

Jeff (Dell-Predator)