This is something that's just cropped up in the past
couple of days. I'm subscribed to about 45 feeds and I
leave items of particular interest as unread, sort of like
a "bookmarking" feature. Two days ago, everything in
one of my categories was marked as read after a reboot.
I never clicked "Mark all items in category as read" or
pressed Ctrl+M while the category was selected. I'm
running Win XP SP2 with all of the latest updates
including .NET Framework 1.1 SP1.