Try removing all one stick of RAM to see if it makes a difference.
There are also reports that slipstreaming more drivers than needed to get installed can cause problems.
One experiment you can try is to install XP to it's native PC or an older one that accepts it, then move HD or an image to the newer hardware. From Windows 7 HD or partition run Paragon Virtualization Manager
on the XP partition supplying the same drivers which will only be loaded as needed.
This is a much more advanced method that always works to adjust an OS bootable on other hardware to new hardware unless it reports it cannot find a key storage driver.