Oh dear that possibly doesn't look good (scrn1 shot),
Last time I seen something similar to that the memory on my graphics card was damaged and the card needed replacing. First off I would try running a few other games to see if the same thing happens to them, play for a good 20 mins or so on each to give things a chance to show anomalies.
Few things to try first off :
Add the splash and screen startup and main file to DEP (Windows Vista, 7 & 8)
Start > Control Panel > System > Advanced System Settings (Top left side of screen)
Window will pop up and will show Advanced tab at top, now click settings beside the bit that says performance
Next Window click Data Execution Prevention tab
Click button for turn on DEP for all programs and services except those I select (This will allow you to add files).
Click Add at bottom and navigate to your installed directory and select Sum.exe, do it again and this time select Summoner.exe and after both these files are in the window click Apply at bottom.
Now try running the game again.
In the setup on splash screen after detecting your video card try both 3DFX Glide and D3D
Re install Direct X
Re install your graphics driver after cleaning with Driver Fusion (Uninstall driver, then clean, then restart and re install) http://treexy.com/products/driver-fusion
Make sure to install in root directory (ie : D:\Summoner) and run setup as administrator, you could also try setting the Sum.exe and Summoner.exe to run as Administrator once installed.