Posts disappear after ‘More’ link

Help please, especially after automatic WP version updates via Fantastico… random blogs posts are getting chopped off and disappearing completely past the “More” link.

I read on the forum that if the “More” link was included within a paragraph it might cause a problem. If so, what causes this and shouln’t WP users be warned quite visually about this on the dashboard.

But there are posts in which the “More” link was correctly between paragraphs, and they have got chopped and completely disappeared as well.

I am in pretty big trouble as I opt to only keep my latest WP MySQL database backup.. letting it overwrite the previous backup. So it is looking like I need to manually rewrite some 100 posts – any help is most welcome, particularly so this does not ever happen again.