Last weekend I installed 9. I used the machine for a day or two, then left it sit for about a week.
This morning I turned it on. All seemed well until I tried downloading a file. It got to about 98% then said "Unknown Error".
My next thought was to reboot, zap the pram and rebuild my desktop, then check the disk with norton.
Imagine my surprise when it automatically booted to Norton and asked me if I wanted to format my hard drive!
It took six or seven times through disk doctor to get all the errors exorcised from the drive. Then I ran Disk Doctor once more to verify the media. Thankfully, no problems.
The primary problem was my master directory block was toasted. Once that was fixed, everything else seemed to fall into place. Then came the relatively simple process of reinstalling the OS. I stuck with 9, though I'm thinking I should have just gone back to 8.5.
9, for all the under-the-hood improvements, has been one nightmare after the other for me. Are there any REALLY beneficial improvements? All I've seen so far are its destructive capabilities. I WANT to like it, because it's the MacOS, but so far I've not seen any compelling reasons to upgrade, and more than one reason to step back a version.