A7N8X-E D +XP and Stand-by

I'm running XP Home, AMD 2800+ with a WD 160 HD (XP) as slave to an IBM
Deskstar 34.2 GB, master with Win98SE and I can't seem to get the computer
to come out of St.by or Hibernate mode,(XP) without having to re-boot.

XP is SP1 and I've applied all patches /hotfixes, even added the
'WaitOnBusyOnPowerUp' string to the Atapi secion in the Registry.
Does anybody have any insight as to why my computer will not resume normally
after St.by or Hibernate? I've tried Bootvis, but that tells me nothing.
Video card is a Matrox G400 dual head.
Many thanks
PS

My partners had the same problem with a memory conflict, the system
memory didn't like the 3D Prophet 4000XT PCI and caused the system to
hang when it went into standby. It's an old board so we put up with
it....

angie