I just switched it and I get the exact same error message(and I did try that once before)...that's what I find so darn odd. Here's the entire listing of the file.

template <class T>
class L_Stack
{
public:
L_Stack(void);
int empty(void);
int depth(void);
void push(const T);
int pop(T &);
int peek(T &);

Node *last; //the top of the l_stack
int size; //how many elements currently in the list
};

template <class T>
L_Stack<T>::L_Stack(void)
{
size = 0; //nothing in the list
last = NULL; //no nodes
}

template <class T>
int L_Stack<T>::depth(void)
{
return size; //the size of the stack
}

template <class T>
int L_Stack<T>::empty(void)
{
return size == 0; //if the size is 0, then the stack is empty
}

template <class T>
void L_Stack<T>::push(const T x)
{
append_node(x); //make the new node
size++; //increment the size of the list
}

template <class T>
int L_Stack<T>::peek(T &x)
{
if(last) //if there's a node there
x = last->data; //show the data, don't delete the node

return 1;
}

template <class T>
int L_Stack<T>::pop(T &x)
{
x = last->data; //set the x
remove_last_node(); //get rid of the node
size--; //decrement the size of the list

return 1;
}

/***********PRIVATE FUNCTIONS*************/
//when we're adding a node in a stack, it ALWAYS goes on the *last
template <class T>
void L_Stack<T>::append_node(T x)
{
//Node *temp = new Node;
L_Stack<T>::Node *temp = new L_Stack<T>::Node;

temp->Prev = last; //set the prev
temp->Next = NULL; //set the next
temp->data = x; //set the data
last->Next = temp; //fix the last

last = temp; //make a new last
}

template <class T>
void L_Stack<T>::remove_last_node(void)
{
Node *temp = last; //temp var to be destroyed

/*This is where the doubly linked list comes in handy! You don't
have to search through the list of nodes to find the PREVIOUS(Prev)
node so we can do this operation. This cuts down on seek time a lot,
as well as cleans up the code*/

//the previous node now points to NULL
last->Prev->Next = NULL;
//delete the last node
delete temp;
}

L_Stack<char>::Node *temp = new L_Stack<char>::Node;

If that doesn't work, the error might be more explanatory.