Just did a search in these forums looking for support on this issue.
I've read elsewhere of people having their entire website go blank. Not the case here, just select posts. Not all posts, just a handful of specific ones.
I found out that WP Super Cache was the issue because I disabled ALL plugins on my site. Then methodically went through one-by-one to determine which plugin was the issue.
WP Super Cache was the last plugin I activated in the testing, and it was the plugin that made the error repeatable. With the plugin installed and active - error of blank page. When the plugin is disabled and inactive - no error.
Not sure how to proceed. But for now the plugin is off.
Using WordPress 3.0 and Thesis 1.7.
Let me know if you have any questions.
Willing to run some tests, etc to help debug what may be the underlying cause.