Not bluetooth related but I’ve seen something similar with USB3 on my mothers laptop.
What it turned out to be is intel stupidly reused the pci ids for the next generation of controller, the driver is not actually compatible, and their website will also give you the wrong (i.e haswell not ivy bridge) one. trying to install the haswell usb3 driver on an ivy bridge system causes a bsod, but at no point does anything tell you it’s the wrong driver and as the pci ids were reused the system will accept it and try to install/use it.
Thanks, @Peter_Schofield. I tried once more with downloading the file first from the Intel website, rather than using the Assistant, but with the same result. So I’ve blocked that particular update and will wait for another one. My Bluetooth is working fine already so I have no need to update.
I would be interested to hear, though, if anyone else has had the same issue with this update.