After the Piano scene there is a video being played in the kitchen.
Unfortunately the engine freezes on some computers when the video is showing.
This is a known bug and is very hard to consistently fix since it's so sporadic and maybe even hardware dependent.
I apologize for the frustration.
I implemented a workaround while I work on a consistent fix.
Fix:
After the piano scene the game does an autosave.
Load the save file and head to the kitchen.
Now, instead of clicking the pizza on the table talk to your dad.
He'll ask you about the bug and teleport you right into the next stage of the game.
Again - Sorry but it's kind of out of my hands. I'll do my best though!
Thank you very much,
KoKo