[petek]

I had a similar-sounding problem installing 10.2.3 on a beige G3. It would get about half-way through installation and the screen would go off and the computer hung.

I eventually tracked it down to the Epson printer drivers it was trying to install! No idea why they caused the install crash, but doing a custom install without them worked. I then updated to 10.2.4 which installed okay - it put in later rev. drivers.

What machine are you installing on? Did you reformat the HD, run Disk Utility, etc.?