Yesterday I was having quite a bit of trouble of getting rid of a flickering mouse / graphical issue on both Arcanum and Planescape. I finally found the cause of the problem and figured I might as well leave it here.

The infinity engine (I believe it's called) cannot handle 'crossfire' (for ATI) or 'sli' (for nVidia) setups, basically two videocards that work together. Some high-end cards, like the one I'm using, have a crossfire within a single card.

When disabling one of these two 'cores' the problems seem to dissapear, though this was not as straight-forward as ticking a button. The solution here is only for ATI cards, but I'm sure there are ways to disable one card with nVidia setups as well.

By disabling the ATI Catalyst AI, you automatically disable one core. ATI removed the setting to do this in recent versions of the control panel, so here's how to do it manually:

1. In CCC set up your AA & AF settings, make sure that Catalyst AI is set to "High Quality", and make sure that the "Enable Surface Format Optimization" check box is unchecked before continuing.
2. Search for a file named 'Profiles.xml'. It's located in the AppData folder, which is hidden by default (just type it in the location bar of explorer). Mine was located here: C:\Users\YourName\AppData\Local\ATI\ACE\Profiles.xml
3. Right click on the file and select "Edit".
4. Find 'CatalystAI' and change Enable to Disable
5. Now run the MOM.exe file. Mine was located here: C:\Program Files (x86)\ATI Technologies\ATI.ACE\Core-Static\MOM.exe
6. Restart your PC

Don't forget to revert these steps once you want to play heavier games again, as you're basically cutting your speed in half by disabling a core.

Note that besides this tweak, I also applied the '-no3d -doublebuffer' fix, though I haven't tried to run it without this.