Hello OldHarry,
The screenshot of the error indicates that the Mod-DLL wasn't loaded, but the default DLL. (Some array y sizes are related to the MAX_PLAYER-constant and this is changed in the RtR-Mod. This leads to a immediate crash at entering the PB loading screen.)
Could you upload your Ini-File? I'm wondering what setting of this file could be problematic (if the problem is releated to the file content at all.) What happens if you put the mod name into the Ini-file, but remove the 'mod= ...'-part from the startup command?
Moreover, please try out if the game also loads if you use the provided Civ4BeyondSword2015.exe instead of the normal one. (Depending on your post, 'old disk-based installation', I do not expect that it helps, but a quick test is better as speculating
)
The screenshot of the error indicates that the Mod-DLL wasn't loaded, but the default DLL. (Some array y sizes are related to the MAX_PLAYER-constant and this is changed in the RtR-Mod. This leads to a immediate crash at entering the PB loading screen.)
Could you upload your Ini-File? I'm wondering what setting of this file could be problematic (if the problem is releated to the file content at all.) What happens if you put the mod name into the Ini-file, but remove the 'mod= ...'-part from the startup command?
Code:
; Specify a Mod folder (Mods\Mesopotamia), '0' for none
Mod = Mods\RtR_4.0.9.2
Moreover, please try out if the game also loads if you use the provided Civ4BeyondSword2015.exe instead of the normal one. (Depending on your post, 'old disk-based installation', I do not expect that it helps, but a quick test is better as speculating

Code:
"C:\Program Files (x86)\2K Games\Firaxis Games\Sid Meier's Civilization 4 Complete\Beyond the Sword\BTS_Wrapper.exe" Civ4BeyondSword2015.exe ini=C:\civ4ini\CivilizationIVpb42.ini
or simply
"C:\Program Files (x86)\2K Games\Firaxis Games\Sid Meier's Civilization 4 Complete\Beyond the Sword\BTS_Wrapper.exe" ini=C:\civ4ini\CivilizationIVpb42.ini