[oofangus]

Man, this sucks. I can't believe that there's no simple uninstall for a bloody OS patch. Or, that I'd need to pay for a third-party program to uninstall it.

At any rate, I decided to manually rebuild the phone from scratch. Like big Windows, I find that Windows Mobile only behaves well for about 6 months before spurious errors begin arising. In this case, there was an annoying beep whenever I pressed the hardware END button. I'd been avoiding doing a rebuild just for that, but the hotfix/Bluetooth issue was a good enough excuse to take the plunge.

The good news is that my Bluetooth functionality is working again. As a test, I also explored the phone's Bluetooth immediately after reinstalling the OS, and again immediately after installing the problematic hotfix (with no other customizations in between). I did the test twice: in both cases, Bluetooth worked after installing the OS, then failed after installing the hotfix. So, I'm convinced that this is a generic problem with the hotfix (or possibly hardware?), not a configuration problem specific to my phone.

I've notified HTC about the issue, and a representative replied that he'd forwarded my message "to the right department".

Thanks, everyone, for your suggestions along the way.

-Michael