yet another blank white page

Here’s another “blank white page” issue…

When I go to “publish” or “Save” a new post, I get a blank white screen. Nothing is posted to the database, either – so it’s not saved.

I’ve tried disabling all plugins and functions files; switching the theme to default; editing my wp-vars.php and wp-settings.php files (the latter, I couldn’t find how to disable the cache – isn’t there a way to do that with wp-config.php? I thought I saw that once…) as directed by a bug report for 2.0.x; and clearing the browser cache. Oh yes. and going to options>writing and clearing out the “update services” thing, as well. No effect from anything. So…any other ideas for me?