strange flickering followed by color inversion

[Matt Price]

hi folks,

i'm going through a bunch of minor inconveniences this week...  

ever since i got my laptop this summer (dell latitude d820) it's been
afflicted by a minor, irritating bug.  after a period of inactivity,
just before the screensaver engages, the screen goes through a few
seconds of violent flicikering.  THen the screensaver engages and seems
to be working fine.  however when I press a key to go back to my
desktop, the colors are entirely reversed so that e.g. white backgrounds
are black, and as a consequence almost everything on the desktop is
illegible.  I'm not sure whether this is a bug in the xorg,
gnome-screensaver, or the nv x driver (I doubt it's the latter, though,
as I've noticed the same phenomenon with the nonfree nvidia driver).  

my graphcs card is an nvidia something.  hwinfo says the following:
28: PCI 100.0: 0300 VGA compatible controller (VGA)
  [Created at pci.277]
  UDI: /org/freedesktop/Hal/devices/pci_10de_1d8
  Unique ID: VCu0.a31GnJCtPl7
  Parent ID: vSkL.rxAOeWuq8i6
  SysFS ID: /devices/pci0000:00/0000:00:01.0/0000:01:00.0
  SysFS BusID: 0000:01:00.0
  Hardware Class: graphics card
  Model: "Dell GeForce Go 7400"
  Vendor: pci 0x10de "nVidia Corporation"
  Device: pci 0x01d8 "GeForce Go 7400"
  SubVendor: pci 0x1028 "Dell"
  SubDevice: pci 0x01cc
  Revision: 0xa1
  Memory Range: 0xdd000000-0xddffffff (rw,non-prefetchable)
  Memory Range: 0xc0000000-0xcfffffff (rw,prefetchable)
  Memory Range: 0xde000000-0xdeffffff (rw,non-prefetchable)
  Memory Range: 0xdf000000-0xdf01ffff (ro,prefetchable,disabled)
  IRQ: 9 (7 events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v000010DEd000001D8sv00001028sd000001CCbc03sc00i00"
  Driver Info #0:
    XFree86 v4 Server Module: nv
  Config Status: cfg=new, avail=yes, need=no, active=unknown
  Attached to: #13 (PCI bridge)


any suggestions on where i might look to figure out what's causing this?

thanks,

matt

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