Hang on. You said you keep doing a whole new reinstall, but you never say anything about how you're uninstalling the old one. Did you delete the SoA folder and everything in it?
When you use the Install Shield uninstaller to uninstall Baldurs Gate or Baldur's Gate 2, you never completely uninstall the game. Sure, the game itself is no longer resident on your hard drive, by you've still got that Override folder and WeiDU log sitting there. You have to manually delete these two files after you have uninstalled the game and before you reinstall. Nothing fancy. Rightclicking and selecting "delete" will work.
There are several files that are not removed during uninstallation. The Override folder, the WeiDU log, all your mods, your saved games, your custom character portraits, and sounds are some of them. The uninstaller will not remove your mods, either.
Unless you delete your WeiDU log, it is going to tell your computer to reinstall everything in the log all over again. But it won't do so cleanly, so you will probably see strange lines crop up.
Hope this helps.