I have the same problem on my server. Linux debian 3.1. If i change the files (only modules and the dll) to 1.76d nvault will not load. Switched all possible combinations, nvault will only load if all files are from 1.76c. Strange. I have mailed my files to sawce and they loaded fine for him.
Tried to enable the module in the modules.ini didn't solved the problem, still bad load in amxx modules.
Maybe it is related to our OS SubStream?