Okay, my apologies for not saving a screencap, since I wound up needing to leave the computer after this happened.
After entering my name and waiting to get logged in, I clicked on the ladder for an NU match. After about 10 minutes of waiting, it seemed like it was bugged out and just not working. So I asked for an NU match in the chat, and got a challenge, which I accepted.
Naturally, after about 12 turns or so, the ladder matched me up with someone else. Before we selected leads, I apologized to them and left, since I was already in the middle of another battle (and I honestly don't care about my ladder rating).
This is where things started getting weird.
After I closed the rated battle window, I saw "Malkyrian has forfeited. X wins", with X being the opponent from the rated battle. The problem is that I saw this in the unrated battle window, which then didn't allow me to select any move to use.
After explaining to my opponent what was going on, I tried opening the battle in a different tab...in which I was under a guest name. I entered my name into the box there, and eventually got impatient, so I tried closing the tab with my name on it, and I as the guest was allowed to take over for Malkyrian who had left the battle, with my own team. The battle went normally until about a minute later, when the login server gave the guest account the Malkyrian name, at which point I had to take over again...and promptly saw the "victory doesn't mean anything" message, even though the battle was still ongoing.
It seemed pretty much normal from there (barring the complete absence of critical hits amid a massive PP stallfest), though I have no idea what was going on on my opponent's end, since they didn't say anything at all.