1 : are you sure its the Create Poly tool? 2: You should not need to snap back at the end, the Create Poly is already a closed polygon. 3: Give us some screen shots to have a look, as this sounds wierd.
The only thing I can think of is you have snap to grid enabled and you might be looking at it end on, though I dont know thats possible.
Cheers bullet
bullet1968
"A Darkness at Sethanon", a book I aspire to model some of the charcters and scenes