in bank.c
find

   /* Create a new account with amount deposit */
   if( type == BANK_CREATE )
   {
      if( uall )
         amount = ch->gold;
      else
      {
         if( amount <= 0 )
         {
            send_to_char( "You need to at least deposit something to open an account.\r\n", ch );
            return;
         }
      }
      if( !( bank = new_bank( ) ) )
         return;

change that to this

   /* Create a new account with amount deposit */
   if( type == BANK_CREATE )
   {
      if( uall )
         amount = ch->gold;
      else
      {
         if( amount <= 0 )
         {
            send_to_char( "You need to at least deposit something to open an account.\r\n", ch );
            return;
         }
         if( !has_gold( ch, amount ) )
         {
            send_to_char( "You don't have that much gold.\r\n", ch );
            return;
         }
      }
      if( !( bank = new_bank( ) ) )
         return;

Can you say oops. Everyone using the code should fix this one, that can be a very bad issue lol.