Couldn't tell that anything out the ordinary (e.g., bills paid) changed on the report. I think it was truly a "technical" issue, as opposed to something wrong with the credit file itself (e.g., a security breach). I guess that's why neither of the Equifax CSRs I talked to mentioned a security freeze or anything like that on the file. Whatever the bug was, they apparently found it and killed it. I had asked one of the CSRs whether this happens a lot, to which he responded "it has happened to others before, yes."
Starting Score: 542 (in 2006)
Current Score: 661 (TU FICO), 677 (EQ FICO), 672 (EX FICO)
Goal Score: 750+