Troubles during Upgrade

Upgrading from 10.5.2 (iATKOS) with either MBR or GPT, to:

• 10.5.3 kills my wireless mouse
• 10.5.5 causes looping through POST/bootp/reboot

Details:

Trying 10.5.5 with this technique

Results:
pre: ok
10.5.5: ok
post: ok but, during choice of customizations, display/monitor casually dimmed to black, system froze, then a hard reset gave:

• POST (normal)
• looping through POST/bootp/reboot
  

I guessed (incorrectly?) that MBR had been overwritten, so I tried 'fdisk -u /dev/rdisk0', which rewrote MBR. This didn't help. I suspect since 10.5.5 installation (esp. bootloader) didn't finish, startup was left untidy.

Booted DVD and, while too scared to try OSX-clean > OSX-primary, I continued DVD install to "Move user settings from partition", and chose OSX-primary. All but video driver restored.

(currently working here)
(re)trying http://forum.insanelymac.com/index.php?showtopic=109102&start=1500:
PartitionMagic to copy SATA2 to SATA3
set rez back to 1024 x 768
test fallback by booting from SATA3

Results:
pre: ok
10.5.5: ok
post: chose:

• 9.4.0 StageXNU Kernel
• restore audio
• restore network

result: (same as above)

Giving up and using 10.5.2 for now.