I see blank page while trying to view a post published in new category

Hi there,

Today I encountered a strange problem when publishing a new post on my blog. I created a new post and assigned it to a new category. When I tried to preview the post, everything seemed to be ok. But when I finally published it, and went to my blog and tried to view it, all I could see was just a blank page. The index page of the blog was ok, and i could see the new post, but when i tried to open the full article the problem occured. Everything else (the index page, older posts were ok).

I tried to search for a solution of my problem in previous posts on this forum but nothing worked. I disabled all plugins, went to phpmyadmin and optimized and repaired all tables etc. but nothing worked.

Finally I went again to the admin panel, and changed the category of the post (to a one that already existed) and suddenly the problem disappeared. But when I again changed the category to the original one, the problem occured again.

Do you know what may be the cause of this problem?