It is indeed broken, it is a programming error. You cant fix it unless you compile the correct source.

Simon if you read this, you should fix the bug with this:
its in main(), changes are bold:
if(y>0 && y<sdl_scale*YRES && x>0 && x<sdl_scale*XRES){
int cr;
cr = pmap[y/sdl_scale][x/sdl_scale];
if(!((cr>>8)>=NPART || !cr)){
#ifdef BETA
sprintf(heattext, "%s, Pressure: %3.2f, Temp: %4.2f C, Life: %d", ptypes[cr&0xFF].name, pv[y/CELL /sdl_scale][x/CELL /sdl_scale], parts[cr>>8].temp, parts[cr>>8].life);
#else
sprintf(heattext, "%s, Pressure: %3.2f, Temp: %4.2f C", ptypes[cr&0xFF].name, pv[y/CELL/sdl_scale][x/CELL/sdl_scale], parts[cr>>8].temp);
#endif
} else {
sprintf(heattext, "Empty, Pressure: %3.2f", pv[y/CELL/sdl_scale][x/CELL/sdl_scale]);
}
}

Really you shouldn't need to use scale:2 to scale the program, either there should be a larger resolution of the simulation (which could cause some slowdowns on systems) or there should be an in-game option to have the particle grid be 1x1 or 2x2 (scale:2 size) pixels [I'm not sure how big the fluid simulation grid is but just double the values].

I was saying ways that the program could avoid the use of scale:2 as it's not exactly a pretty fix.

Looks like it has been fixed in 37.0