> I disabled the guardian, made the main Firebird service automatic and the problem persists. The system refuses to boot until I disable Firebird totally. I can start Firebird manually after the system is booted, no problem.
>
> Any ideas?
>

It is looking like this turned out to be a hardware problem. The motherboard eventually failed completely and since I had it replaced the problem has not recurred. Odd that only Firebird was affected, but that's computers for you.