[THEBERBSTER]

Hi sIII

If I remove Ahnenerbe's d3d9.dll I get the 1024x768 screen, but the game plays.

Well, that is positive news as I would say it rules out any driver issues.
It would appear if the game runs in stock then it is not a Direct X problem.
We know the stock game default resolution setting is 1024 x 768 with an aspect ratio of 4.3 which is why you get the bars down the sides.

I take it you are using the correct version of Ahnenerbe wide screen mod the one known as 'final'.
Ahnenerbe's mod when used in LSH3-2015 is never fully wide screen unlike the LSH3-2015 widescreen mod which is.

It could be a resolution size in the d3d9 config settings.
Check the display height, it should be greater than 1024, probably 1360.
It could be a resolution size in the SH3 main cfg file video settings.
This should represent your monitors resolution or close to it.
Peter