Are you using "PLasv1a" for terrain? PLasv1a is a UOP in it's own right. Some have problems with it when used with other UOP's, most don't. You could try loading HASP AFTER PLasv1a.
Files are cross indexed between DATA/lowres.vol and the #DPatch vols with PLasv1a, and as Wailwulf said there will be problems unless they are all present. Since you apparently prefer PL1 terrain, another possible solution is to unpack PLasv1a to a working folder then COPY "lowres.vol" to DATA and the 3DPatch VOLs to 3DPatch folder in your RB install. This leaves the PL screens and sounds and other stuff behind.
Also note that End of Mission DDT's (Drop To Desktop)are debrief crashes (debrief fails to load)- so be sure to DELETE "debrief.dat" from RB folder before running the game again.