You are holding down the keys too long. Release the Command-Option-Shift-Delete keys immediately after seeing the Welcome to Macintosh screen.
Here is an alternate solution that can be used if the system has started up and the internal hard drive does not appear on the desktop: On the CD, in the Utilities Folder, is Drive Setup folder. Run Drive Setup, select the <not mounted> list item by clicking once on it, then select Mount Volume from the Functions menu.