tech.q: FC4 install hangs right after graphical Anaconda starts - any hints?

[Frantisek Rysanek]

Dear everyone,

the subject says it all - the graphical Anaconda hangs just 
after the Xserver starts (with the mouse cursor moving) and 
the GUI gets displayed.
Even while the widgets are being rendered for the first time, 
the system is alive (NumLock works, mouse cursor arrow moves). 
But, just after the "Welcome to Fedora" screen becomes fully 
rendered, NumLock stops responding and the mouse stops moving.

The machine is a P4 Celeron at 1.7, in an original Intel 
desktop board based on i845 (Phoenix BIOS). The graphics board 
is an S3 Trio 64V+. The original memory size was 256 MB,
I tried upgrading it to 750 MB to no avail.
The keyboard and mouse are both generic PS/2 types, inserted 
into their respective sockets.
Generally all the hardware is "known good", works just fine in
RH8.0 with various vanilla 2.4 kernels.

Any quick hints are welcome :-)

Frank Rysanek