Sure enough, the site worked fine this OS and browser. It wouldn't take my credit cards which I don't understand, but that's a separate issue.
Then I decided that I hadn't heard from my Discover card in a while, so I'd go check out how that debt was doing. I'd been paying bills earlier today and came across the form they'd sent me to request a lower rate on my card. (Trickily, they won't let you ask for a "lower" rate, you have to ask for a specific one which they will approve or deny. If you're denied, you have to make the request again. Meanwhile, you get charged the higher rate. Bastages.)
I fretted myself a bit for carrying a few thousand dollars on that card, particularly at an obnoxious interest rate. I was paying bills earlier and so feeling a bit flush with the cash; I decided I'd check in an make a payment ahead of schedule (or just in time if I'd somehow missed a bill).
Upon logging in I was a bit confused to see that I had thousands of dollars of available credit. Then, upon looking at the transactions, I remembered that I'd sent them a large check from my house refinancing! Oh, yeah!
So this means that I currently have less than $600 of credit card debt (and less than that, if you figure in the over-payment made to my U of M Credit Union Visa card).