This is most likely due to RP 1.2 containing ancient version of sfall.
1. Get latest
sfall
2. Extract is somewhere (it's compressed with
7zip but other exractors, like winrar, may be able to extract it but I only use 7zip my self so I can't be sure)
3. Compare the old ddraw.ini in your fallout 2 folder to new one and copy any settings that are different from old version to new version (ignore any setting that no longer exist in new ddraw.ini)
4. save changes and copy new sfall files to your fallout 2 folder and overwrite
5. see if game runs
6. if game still fails with same message right click game shortcut, click properties -> compatibility -> make sure all compatibility settings are off.
7. try to run the game
8. if problem persists set SkipCompatModeCheck to 1 in ddraw.ini
9. try to run the game
10. if it still fails come back here, I'm sure timeslip (the author of sfall) will be interested in your problem by then.
