Harrington shot his second-successive 66 to share the halfway lead in Cologne, Germany with Michael Campbell. At 12-under-par, Harrington and Campbell are one shot clear of first-round co-leader Jose Coceres; and two lower than Thomas Bjorn and Bernhard Langer.
A year ago at this event, Harrington lost out in a sudden-death playoff to Sergio Garcia. It was one of five runner-up finishes for the Irishman in 1999.
Last week, Harrington led through 54 holes of the Belgacom Open, but faltered on Sunday to finish third.
But it was earlier this year that Harrington suffered his greatest disappointment. In search of his second victory of the season at the Benson & Hedges International, Harrington took a five-shot lead into the final round. Unfortunately, the 29-year-old was disqualified just minutes before he was set to tee off.
It was discovered Harrington had not signed his first-round scorecard.
He's been haunted by that episode ever since.
'It's put a lot of pressure on me because I played so well that week,' Harrington said of the May incident. 'I'm trying to forget, but it's taken me four months to realize I've been trying to live up to that week ever since, trying too hard because of it.
'I don't know what a win now would do for me. Perhaps it would be better to focus on winning for the sake of winning, instead of trying to get rid of a bad memory.'
Friday, Harrington recorded an eagle and four birdies to maintain a share of the overall lead at the Gut Larchenhof course. Ironically, Harrington will be paired with Campbell in the third round. The Kiwi was one of his markers on that disappointing day in England.
Campbell earned another chance to play alongside Harrington by shooting a one-eagle, six-birdie 64. In fact, Campbell had birdie putts on each of his final two holes to equal or beat the course record of 63.
'The last time we played together it was unfortunate and not good memories for Padraig, but that's long gone now. Water under the bridge,' said Campbell.
'Don't worry, I will probably triple check Padraig's card tomorrow!'
The German Masters' leaderboard is a veritable 'who's-who' in European golf. Bjorn and three-time German Masters champion Bernhard Langer are tied for fourth. 1998 German Masters champion Colin Montgomerie is just three shots off the lead; tied for sixth with first-round co-leader Angel Cabrera, Jean Van de Velde, who shot a second-round 64, and Adam Scott.
Order of Merit leader Lee Westwood is in a four-way tie for 10th at 8-under-par. Defending champion Garcia is at 7-under, five back entering the weekend after a Friday 65.