Are you referring to the FS9 version ? I'm assuming yes, because you called it bglman.dll, while the FSX version is called bglmanx.
In any case, it's just not possible for a plugin module, that is loaded and unloaded by flight sim, to prevent Vista from starting (considering also the Vista built in system files protection) so, you probably already had other problems that don't have anything to do with flight sim or the Addon Manager, that you just noticed now.
We all use both FS9 and FSX version of it under Vista 32 and, of course, no problems at all, and I guess a lot of people are using this config, and nobody ever reported such problem before.
