If the method above failed and you have tried the solutions referred to in the game support articles (log in, click support, scroll down to SG and click the support articles to the right of the game icon ) then I only have a couple of suggestions.
By modern system, I assume you are running Vista / Win 7. Make sure you are running the game as an admin. Right click the game icon, click Properties, click the Compatibility tab and check mark the "Run this program as an administrator"
Make sure you are running the latest video drivers. I had a similar problem which was fixed by updating my six month old video drivers. Nvidia ATI
Many Intel cards will not run Sacred (see the support articles)
If you have an AMD Dual Core CPU you might try the AMD Dual Core Optimizer
. It fixed some stutter problems with PK on my laptop. I also have SG installed but I already had the Optimizer installed so I don't know if it helps SG. SG runs great so . . . it doesn't hurt. It will not work on an Intel CPU or on a single core AMD system.
You could also try RunFirst
. It is a small, free program that sets the affinity to a single core on multicore systems. It will not work on a single core system.
Setting the affinity to a single core on multicore systems sometimes clears up some nasty graphics problems. You can do it manually by starting the game, open task manager (CTRL - ALT - DEL ), find the Sacred exe on the Processes tab, right click the exe and click Set affinity . . . on the resulting dialog. Un-check all but the CPU 0 check box. Close the task manager and play the game. If this helps I suggest using RunFirst as it sets the affinity for the game without having to go thru the task manager process each time you play.
Hope you find a solution . . . =)