I know this has been brought up by other posts, but I too experience "unspecified error" CTDs regularly and cannot fix them.
I have tried reinstalling everything (Medieval, patch 1.5, SS6.3 and 6.4) as an admin, with all UAC turned off and with ME2 exempted just in case. All drivers are up-to-date. I also tried disabling autosave too.
I even tried installing and playing SS on a recommended compatibility mode ( I have Windows 7) but nada. I installed the game on both C and not-C drives, nope. This CTD happened throughout a long Early Start campaign I had and it eventually ruined my game, effectively ending it at turn 116. No submods, just SS6.4 on Savage mod and perm watchtowers.
Now the same CTD happens frequently in a new HRE game. My systemlog is attached and I will try to get the save game in. This ruins the mod for me so help is needed.