Why does GoodSync and Windows Explorer sometimes show file modification times that differ by 1 hour?
Because of bug in Windows Explorer. Let me explain: Say, you have a file modified in in 2:00:00 PM on Nov 24, 2008. And today is November of 2009. Both GoodSync and Windows Explorer show the same file modification time. Fast forward to summer season, July of 2010 and this file did NOT change. Now GoodSync still shows the same file modification time: 2:00:00 PM on Nov 24, 2008. But Windows Explorer show time shifted by 1 hour: 1:00:00 PM on Nov 24, 2008. So Windows Explorer shows you the same modification time as two different times, depending on the current DST setting (is it summer time or winter time). GoodSync always shows the same file modification time.