Various post gets 'archived' and doesn't show full post after more button?

Hi, I have my blog as ‘blog image large setting’. all the posts have shown full content after clicking the more button, until one day one of the posts did not show all content even after pressing ‘more’ and the title changed to post name-archive. i had to change the permalink to a different name for it to show up again. why does this happen and how can i make sure it doesn’t happen again? i don’t want to have to check every post’s read more button to make sure my content is there…

thanks for all your help!

This only can be possible if you had two pages(archive,post page or any other) with the same permalink. So WordPress got confused what to display. Other cause could be your servers’ apache rewrite rules.

This, in fact, is WordPress related and I have no control over it via theme.