As you might expect, it was my fault all along. :) I modded comments.php for a different plugin and didn't undo those mods. Sorry to waste your time, but I appreciate you taking a look at it for me.

I don't know, but I'll check with my ISP and see if I can get access to the logs. I've deactivated the plug-in and now my sidebar and footer (php below the comments box in single.php) don't show. It could be just coincidence that I was trying the plugin and they're really not related. I'll let you know if the logs say anything. Thanks.

I tried out the Fluid Blue theme and didn't have any problems, even after activating the iG Syntax Hiliter plugin.

Is this an especially large page?

Is there any way for you to check your server error logs? A blank screen is usually a fatal PHP error, and if I could know what the error is, it would help greatly in diagnosing the problem.

Just activated the plug in on WP2.7. When I Post or Preview, the web page goes blank. The URL is right and Firefox reports "done" in the status bar. If I reload, it gives me the POST DATA warning. Fluid Blue is my theme. What is it about my site that's causing this?

The only other plug in that might conflict is iG Syntax Hiliter.