Nearly a month old thread but I wanted to contribute. I own a PC that runs Windows 8.1 - can't wait for 10 - which I use for working on my board, editing my photos, and playing Sims 4. However I just voted for "other" as my daily driver is a Chromebook. It's perfect for my day to day browsing and word processing needs.
I just had this same problem but I already use my email address to log on. I ended up signing in to the client area and then headed to the forums afterwards in order to sign in as my username didn't work either.