Just to add my findings:
I have a 1.6 dated 9.21.2004
Phillips dvd drive
seagate hd (skinny white one)
yellow dvd ribbon **
**samsung memory chips**
modded w/ a cheapmod/m8 (m8.67 ).
threw a seagate 200gb hd in, formatted for f+g, threw some apps on there, all normal
noticed when copying games either via qwix OR xbox>xbox, transfer would die after about 1gb of data had gone.
popped 200gb drive in another xbox, was able to xfer some games onto it.
popped 200gb back in 1.6(b?) fired up a game, let it run for about 10 mins, then freeze.
now i reflashed bios to beta4, reformatted hd (this time it puts extra space on /f/)
things seem to be working, i'll post again if that isn't true.
but: so far as i can tell, the samsung/hynix theory is thrown out the window, i had samsung mem chips and got the same symptoms as those who had hynix.