I remember that there was a readme.txt-file with the game included where it said that if a machine has more than 16MB of RAM the game encounters problems. While I never had such problem when playing the game earlier on my Pentium 100 with 48MB RAM, in DosBox it might be different because it's an emulation and emulates not all parts of an old PC.
What you could try is to set the memory in DosBox to 16MB or 14-12, and maybe that could help
