Problem with Merc 2.2... segmentation fault!

When a player goes up to level 2 and try to save the mud , the mud crash and the following error message:
Sun Aug 24 20:35:27 2014 :: Crash player: Gnrever.
SENAL Sun Aug 24 20:35:27 2014
FATAL ERROR:SEGMENTATION FAULT!
#00:0x00000000

Someone could help me , I need to know which file I have to modify to fix this

It's hard to say with such little information, such as where you got the file from and what operating system you are using, but you could try running it under gdb.

I have a lengthy post about using that to track down segmentation faults:

http://www.gammon.com.au/gdb