Hi ... same story, with me. Since 1 February, when I had 11,300+ links to 131 pages on my site, I've fallen to 5 links to 4 pages. SERPs,
PR and traffic consistent, on all pages, though. Like you, I have no idea and get few answers when I ask on forums. I built the links, progressively, over about 18 months; some of my links date to 20 July 2006, just after the site launched. Maybe just a glitch; hope so. google is apparently re-jigging some of it's services and adding new ones. Maybe we just fell through the cracks. Keep us posted on what happens to your sites. Good luck.