When I boot XP, I see the Windows splash screen, but the monitor goes
into sleep mode, and the logon screen never shows.

If I boot into safe mode, then reboot, I will get the logon screen. At
the next boot into normal Windows, I may or may not get the logon
screen.

I have my cable modem plugged into the motherboard LAN port. In trying
to find a fix for this problem, I am now up to 'Local Area Connection
4'. I tried going into the registry and deleting all references to
'Local Area Connection...', and uninstalling/reinstalling my cable
modem, then rerunning the Network Setup Wizard. I currently have
internet access, but probably won't at the next boot.

MS Knowledge Base has no references that I could find, neither Google
Groups nor the web in general. The closest match was a
continuously-recurring boot...

Does anyone have ideas what else I could research?