I built this machine to work on Vista64, so it is not my main machine.

The original machine is:
ASUS M2R32-mvp
AMD 5600+
2GB G.skill memory
ATI 2600XT x 2 (crossfire)

I used the defaults on the BIOS except to turn off the floppy interface.

Machine runs fine. I'm writing this note on it.

I thought I'd try to put some more memory in it, and purchased 4GB of
the same manufacturer, and same timing.

When I install, the machine will run Vista64. The BIOS checks run fine,
BIOS sees the additional memory, the initial windows bit with the
scrolling line shows up, and goes away.

Then nothing. No disk activity.

After waiting a while, I shut down and restarted. Got the "windows did
not ... window, and had it boot to safe mode. Safe mode launched ok.

Looked around a bit in safe mode, nothing obvious.

Rebooted, reset BIOS to defaults. Same results.

Shut down and removed 4GB memory sticks. Everything works fine.

Suggestions?

Is this most probably a memory problem? or is there a known problem with
my MB/VideoCard combination and larger memory?

My next step would be to take the original 2GB out and put the 4BG in
those positions, but I thought I'd ask for advice first.

Thanks in advance for your thoughts.

Gordon