It may very well be cookies (mmm, cookies!) but I at least don't see the little symbol noting they're blocked for this site. I've decided it's the work of the random occurrence genie, keeping me humble with his hijinks. The new computer, while blazingly fast, has had a few teething problems that I'm still sorting out.
I'm resolved to having the three machines I rotate among all behave differently, even if they have the same browser. Variety being the spice of life and all. Will look forward to your next round of improvements!