I use Firefox, and keep multiple tabs open most of the time, like many others probably do - surfing, searching, up and downloading simultaneously, etc.
So i keep a pimpandhost tab open all the time, too. Occasionally, i'll use the mass uploader (which is pretty cool, by the way) and up a dozen or so pix, and only after they've all loaded, do i notice they're tagged as "guest" - my session timed out while i was surfing!!
So then i have to go back to my user page, get the cookie, and upload them again.
My suggestion is after an upload as a guest, when you get to the codes page, there should be an option like "Create an account and save your pix to a folder? Start pimping today!" or "Log into your account and save these pix to a folder?"
or .... something like that.
Or maybe it's only me who's goofy enough to make this kinda mistake??
Just a thought.