SCDA Single Player under Windows 7
Step 1) Navigate to "<Drive letter>:\Program Files <x86>\Ubisoft\Splinter Cell Double Agent\SCDA-Offline\System"
Step 2) Create a shortcut to "splintercell4.exe"
Step 3) Right click this shortcut and open properties.
Step 4a) Add "-ll" (without quotes) to the end of the "Target:" box, after the quotes; this prevents the "**MUST CHECK**" runtime error.
Step 4b) Go to the "Compatibility" tab and check "Disable Desktop Composition"; this prevents the flickering screen/no start bug.
Try it.
Single Player Resolution Fix (for resolutions over 1280x900)
This needs to be done after you've changed all necessary graphics settings.
Step 1) In the same "/System" folder find and open "splintercell4.ini".
Step 2) Scroll down to the [WinDrv.WindowsClient] section and change "FullscreenViewportX=x" "FullscreenViewportY=y" as required (x and y being your native resolution figures, e.g X=1920/Y=1080)
Optional: Step 3) Right click on "splintercell4.ini" and open properties.
Optional: Step 4) Check the "Read only" box and click apply. This prevents the resolution from reverting, but also prevents you from changing any settings - use it or lose it basically.