I really appreciate the detailed replies.
Not gone, just been trying all of these (and many others from other forums), to no avail; many of which I'd already mentioned trying before in my original post. It was not a cable issue (which is always the number one place to start troubleshooting) because it was doing the same thing with the built-in microphone, as well as several others, all just going through the mic input on the laptop (and also with headphones, monitors, and the laptop speakers). There's absolutely no reason why a piece of software like this shouldn't be able to handle basic line/mic audio input without an audio interface, it just wouldn't make any sense. That's just poor design.
Thankfully, I was able to find a solution, and it was painfully simple, so here's to hoping the hundreds of others out there having the same problem without an answer will stumble upon this: I set the driver mode to MME (32-bit) and it works like a charm, no popping whatsoever. I'm not sure I understand just *why* this was what finally did it, but hey... It works! No complaints here. :)
I'm hardly new to this universe (haha not that I should have to qualify myself), and as I'd said before, was trying to simply come up with a quick and dirty solution that would allow me to open my laptop, any time, any place, and "roll tape" so to speak, and do so immediately ... but also with the ability to seamlessly drop these stacked/edited scratch tracks (as well as any manually entered MIDI melody parts, etc., which is what I love so much about this software) into my ProTools rig later with zero hassle. No power source needed, no extra cables, etc.. This program is the perfect middle ground and blows away any of the junk freeware like Audacity, etc. for this purpose.
I didn't realize I was on the wrong forum, I was in a hurry to find a solution! Sorry!