First issue. Obviously the second stick isn't compatible with either the
motherboard or other stick. This is not an unusual occurrence in and of
itself, although it's not as bad as it once was. In general it's safer to
buy multiple sticks of memory at the same time, but if not, insure that the
different sticks have the same specs and do not buy generic, bulk memory
unless you know what you're doing.
Second issue. Need more data. With what you've stated the most obvious
answer is improper hardware install or faulting hardware. You said you
installed XP on a new drive. That implies two changes. What was running
before and was the platform stable?
--
Walter Clayton - MS MVP(WinXP)
Associate Expert
http://www.microsoft.com/windowsxp/expertzone
Any technology distinguishable from magic is insufficiently advanced.
http://www.dts-l.org