Thanks for your help. I found the PERFECT solution to the problem on www.macosxhints.com:
Open NetInfo Manager (in Applications/Utiltiies) and see if there is a Unknown User (click on 'Users' in the Directory Browser area). If not, you have to add it back in. Create a new entry with the...
I cannot mount .dmg files (does not show up in Finder nor desktop). Nor can I mount CD-ROM discs. Audio discs are accepted, but not software discs. I get error messages that say that there are no readable volumes, giving me three buttons: Eject, Initialize, and Continue...
I have done the...