Latitude D830 blue screen problem

We have several Latitude D830 laptops running Windows XP SP3.  They also have Winmagic SecureDoc 4.31 SP7 encryption software.

The problem we've been seeing is that sometimes the D830s will blue screen when interacting multiple times with USB devices, and once it even happened when turning on the wireless/bluetooth switch on the side.  The errors aren't consistent, however a few times I've seen the message "Multiple_IRP_requests".

I've tried finding updated chipset drivers for the D830.  The latest ones from Intel's website, along with some updated ones that came with the Optiplex 330 & 360s that contain the PM965 drivers.  None of them update the USB driver and looking at the driver files the ICH8 files are always the same as the version we're running.

Any thoughts on how to prevent this?  Unfortunately removing SecureDoc is not an option.

Thanks.