I tried to upgrade my office B&W to 9.1 today. I couldn't do it. I mean, the installer ran and the upgrade was effective, but then when I tried to reboot, I couldn't--I'd get a Macsbug screen almost immediately. I could start up with extensions off, though, so I am assuming it's some kind of extensions conflict. Unfortunately I didn't have the time to putz around with the machine, so I don't know what led to the problem. From what I read here it may well be the Office Manager stuff (I was smart and disabled the Mouseware stuff before I did the installation).
I'm going to be out of town over the weekend, so I won't be able to troubleshoot for a while
I hate that!