ROLEARY....get rid of Microsoft Office Manager (Office 2001). It's never, ever worked right, even the older version under 9.01. That was the only problem I noticed under 9.1. Once that extension would load, the finder would start looping and I'd have to do a forced restart. Otherwise, 9.1 rocks, picked up noticeable speed in opening apps, and my screen graphics appear sharper(???)
I've installed 9.1 at work on a G4 500, and at home on my Pismo500 and beige G3. Not one problem to report...other tham MOM as noted above.
By the way,, why does 9.1 rename the applications folder to "APPLICATIONS (MAC OS 9)? It even threw my Utilities folder in their, which is not where I normally keep it. Could this be a pre-housecleaning issue for OSX?