Can't write to a file when running my code optimized - c

Question

I have a program that writes data to a binary file, it works when I run it in Visual Studio 2013 in Debug mode (no optimization), but when I run it in Release mode, with Maximize Speed enabled, it doesn't work (the file becomes empty)...
Can you tell me why it might not work?
EDIT:
Dr. Memory log of running the application in Release mode, if you see something alarming, please tell me: http://pastebin.com/5s4Z51ZV
Which errors might cause the problem?
Also, should I work on fixing every single one of the errors? or are some of them "false positives"?
EDIT:
After debugging the optimized code via this guide: http://msdn.microsoft.com/en-us/library/vstudio/606cbtzs%28v=vs.100%29.aspx , I found something very weird was happening when I generate a huffman tree (from a priority queue of characters), this is my code:
HNode * generateHuffmanTree(Queue * queue) // generates a huffman tree from a queue of a file's characters.
{
HNode * root = (HNode *) calloc(1, sizeof(HNode));
root->left = dequeue(queue); // gets the two smallest-amount characters
root->right = dequeue(queue); // and puts them into left and right of the root.
root->character = '\0';
root->value = root->left->value + root->right->value;
if (isQueueEmpty(queue)) return root; // end condition, if it's the only thing left.
enqueue(queue, root); // puts the root back in the queue so it can be a part of the process in the next iteration
#ifdef debug
printQueue(queue);
#endif
generateHuffmanTree(queue); // runs the operation again, now with the new root in the queue.
}
I can see in the debugger that the problem is not in queue as it comes in as it should, but it seems to ignore my declaration of root, then when I try to do root->left it overwrites the data in queue. Anyone know why this might happen and how to find a work around or fix it? Or is it even not the problem?

Answer 1

I figured out what caused the problem. It had nothing to do with the file specifically, I had a function initMap that creates a struct: Map m, initializes it with initial values and returns &map to another function. I suspected this might be a problem because it will get popped out of the stack and then the pointer will be to nothing. But since it worked while I tested it (in Debug mode) I left it alone. But appearently it doesn't work. So what I did is Map * map = (Map *) calloc(1, sizeof(Map)); and it worked.
Thanks to mafso and Kalsai for helping me figure it out.