I've just installed GTA IV (with patch 126.96.36.199) and after applying the usual VRAM commandline options and starting the game, noticed a weird colorful line over the screen while playing.
This does not occur in the menu, or between cutscenes (the black part).
Here is the glitch in action, occuring in the first mission, at the cutscene when Niko and Roman enter the safehouse.
I've tried fiddling with the settings, but to no avail (I'm currently running at 720p, all settings at low, shadows disabled and 2x anisotropic filtering; all numerical sliders are set to 20. Definition and VSync are off)
I'm running an i5-6200U with HD 520 graphics, 8GB of RAM and Windows 10 Home.
The drivers are the ones pulled right from Windows Update.