Stuck, like most everyone else...
Well, I got stuck after I clicked the girl-ghost...so I was looking through your reviews to see what to do, and saw this:
"- click the symbol on the floor in the attic
- open the safe
- read the book in the safe
- retrieve the key from the sink
- click on the symbol on the desk in the library
- click Xavier's diary on the righthand shelf in the library
- click on the head in the microwave for a closer view
- click the book on the table in the lounge room
- click on Gwen in the 2nd bedroom
Once all of these are done, you will be allowed to advance to the cellar...
Let me know if you have any troubles after all the above has been completed..."
Well, I went back, and did each one again (except clicking on the girl, 'cause she only appeared once) and...the door still won't open in the cellar. Maybe you should make some kind of indicators to show what's been done and what hasn't...a checklist, sort of, but one that you can't follow like a script ahead of time.
Very cool game, man, I just wish I'd gotten further.