[ns] Error "bailing in Tcl::eval"

[FNKK]

Dear ns users,

I got a problem when using ns2 simulator
When I excute "ns MyCode.tcl" for a while
It stopped and leave an error message "bailing in Tcl::eval"
The error message seems to be written in tclcl-1.19/Tcl.cc as follows

void Tcl::eval() {
  char* p = bp_;
  bp_ = p + strlen(p) + 1;
  /*XXX*/
  if (bp_ >= &buffer_[1024]) {
    fprintf(stderr, "bailing in Tcl::eval\n");
    assert(0);
    exit(1);
  }
  eval(p);
  bp_ = p;
}

It's weird that I never use "eval" command in my code.
My code is a wireless application written in Tcl and there are about
200 nodes in it.
When I decrease the number of node to about 10~50, this error
sometimes disappeared .
The version of ns2 is 2.33
How should I solve this problem?

Thanks!