Jim,
Facebook's Likes and Comments are associated with URLs on your site. Have you changed the URL structure of your site (either by changing menu items, enabling SEO, or anything else). Basically, pages on your site, in general, should try to remain static. That's good for SEO purposes and for Facebook so that what either sees remains there.. it's also good practice in case someone links to a page or bookmarks the contents of your site, so that when they visit that link again, it's not broken.
Hope that helps explain a little, but if a page that you had Like'd (or commented on) hasn't had it's link changed, then paste the page here, and we can investigate if there's something else that might be going funny on that page.
Thanks,
Alex
Likes/comments dissapeared??
