We have a strange issue on a brand new 2.6.2 blog. A long string of text with some html tags was pasted in to the html editor and published (the code is valid). The result is that the post on the front end is blank (the comments box shows up in the content area, but not the pasted text.)
By trial and error, I pasted in the code line by line until I could replicate the issue. It appears to break right in the middle of a paragraph. Adding a single additional character causes the whole post to go blank on the front end. Meanwhile, in the editor, the code still shows, but if you switch to visual editor it is blank. Switching back to html view then goes blank.
If you look in the db via phpmyadmin, the post is there (along with a few revisions as we sorted this out).
We also tried pasting in the code up to the point that it breaks and saving it. Then we went into phpmyadmin and pasted in the remainder of the code, the entry goes blank on the front end.
Now the crazy thing is... I had someone test this on another server using 2.6.2 and it worked fine the first time we pasted it in.
We upped the server limits in both php.ini and wp-settings.php but that had no effect. I can't figure out what the difference is between the two servers.