Similar situation here:
01:00.0 VGA compatible controller: nVidia Corporation G72M [GeForce Go 7400] (rev a1)
Sony VAIO laptop, desktop effects disabled, garbled logout screen
01:00.0 VGA compatible controller: nVidia Corporation GeForce 8600 GT (rev a1)
Workstation, desktop effects enabled, the area where a context menu is appearing displays for a short time some garbage (logout screen is fine though).
Similar situation here:
01:00.0 VGA compatible controller: nVidia Corporation G72M [GeForce Go 7400] (rev a1)
Sony VAIO laptop, desktop effects disabled, garbled logout screen
01:00.0 VGA compatible controller: nVidia Corporation GeForce 8600 GT (rev a1)
Workstation, desktop effects enabled, the area where a context menu is appearing displays for a short time some garbage (logout screen is fine though).
Both use the latest nvidia drivers (177).