Finding out why the new one doesn't work for you would be your obvious first step. Two things you can try: work your way backwards from 2.6 and see if you can find out which version broke, (since I don't have back copies of anything earlier than 2.1, ymmv depending on what's wrong exactly,) and download the modders pack and use the ddraw.dll file from the 'debugging' folder. (Make sure 'Init' is set to 1 in the [logging] section of ddraw.ini, then check the 'sfall-log.txt' file that will be created.) In both cases, overwrite ddraw.dll only. Keep using the ini that came with the RP. The files are here.