One from the annals of the truly bizarre:

	Upgrading a previously rock solid Dell PE350 (Celeron 850 with
	ECC) from 1.5.3 to 1.6_BETA5 resulted in an extremely
	unreliable machine, random panics, NMI errors, all that fun.

	Problem tracked down to third DIMM slot. Putting a single stick
	in any other slot gave a happy machine, a single stick in the
	third slot resulted in a hang just after detecting the pchb:

	pchb0 at pci0 dev 0 function 0
	pchb0: Intel 82443BX Host Bridge/Controller (AGP disabled) (rev. 0x03)
	pchb0: fixing Idle/Pipeline DRAM Leadoff Timing

	Tried three different motherboards, countless DIMMs (ECC and not),
	all give the same behaviour.

	Putting memory in slots one, two, and four also gives a stable
	machine.

	The PE350 is a rebranded intel board, and quite unlike anything
	else in the Dell range. Now I know why.

-- 
		David/absolute		abs@formula1.com