I'm really a newbie, but I did experience a similar problem going from 8.6 to 9.0.4.....
Is Apple Talk on?
If you have more than one choice within Apple Talk... is the correct ethernet connection chosen?
For me, I had to reinstall nearly EVERYTHING in order for it all to work again...
Hope this helps (or, rather, hope someone wiser posts the right answer) ... good luck !!
newtownjohn