Monitor "sleeps" on boot...

PROBLEM:
When my machine boots, I see the video card status/spec text, then the
boot image from my MB, and then the XP Pro "loading" animation screen.
But then when it goes to the login screen for XP
(username/pass/domain), the monitor goes into sleep mode. The only
way I can get into the machine is by booting in VGA mode.

BACKGROUND:
I upgraded the CPU, MB, and video card about a month ago and this is
the second time I've had this problem, but can't get it to go away
this time (first time all I did was boot into VGA, and then reboot and
it came back). I didn't have this problem before I did the upgrade.
The video card is an Inno3D GeForce4 MX 440 w/ AGP8X & 64MB of memory.
I've tried using the latest drivers and still the same problem. Not
sure if it's related, but my machine also has this undesireable
"feature" where it acts like it looses power and reboots, but doesn't
show anything in the event log.

Any idea how I can fix my video problem? It's acting ~almost~ like it
can't handle the resolution, but it was working fine at that
resolution for over a month and then, from a reboot, decides it can't
handle it.

Thank you,
AC