Just a quick followup here:
If our signin process takes to long to complete (network is slow or whatever the reason is), we still attempt to place the snipe.
That's why you might end up with a confirmation message that says something like "Item has ended", yet the status will be "Unable to Sign in".
After everything is said and done (sign-in and bid) we compare the times everything happened and compare it with the end time of the auction. And in some of the snipes in question here, the sign-in completed after the item had already ended.
-Kevin