My Samsung is pretty much spot on. I use iOne Pro with imatch 3.6. Try not doing the Advanced adjustment and tell it Native in Easy Mode.
Also, go to Xrite/GMB and grab the Calibration (LUT) Tester. It does the following (grabbed from X-Rite under Fair Use)
Download: Calibration (LUT) Tester
Version: NA
Release Date: 12/2/2005
File Type: PC - ZIP file
Download: PC Version
Notes:
A tool to check the active video LUT's of your graphic card. For PC (916 KB).
The Calibration Tester checks for the following two aspects of your display system:
1. Checks if your system supports adjustable gamma curves. This is a necessary condition for doing an automatic monitor calibration.
2. If the preceding test result was positive, checks if the gamma curves in your system have been modified. that is, if they differ from straight
lines connecting the points (0,0) and (1,1). If they are unmodified, certainly no monitor calibration performed by Logo's monitor calibrator
is active. If they have been modified, perhaps a monitor calibration made by Logo's monitor calibrator is active, or another tool has
modified them.
If the second test results positive, you have the possibility to turn the gamma curves into an unmodified state by pressing the Reset button.
To install, simply unzip all files into a folder of your own choosing and (optionally) create a shortcut to the executable.
It came back and told me nothing had messed with the gamma. Your mileage may vary.
Seth