header sent error that doesn't seem to have a solution

[wesg]

This is a problem with Wordpress, so I hope it's OK here, but the problem has been bugging me so long that i need more help.

Whenever I save a new blog post, either with autosave or manually, I get this text on the screen:

Warning: Cannot modify header information - headers already sent by (output started at /home6/.../public_html/wp-includes/general-template.php:65) in /home6/.../public_html/wp-includes/pluggable.php on line 770

Now, I know what the error means (something is outputting text before the header changes locations) but the referencing text doesn't seem to make sense.

Here is the text around line 65 of general-template.php
64. function bloginfo($show='') {
65. echo get_bloginfo($show, 'display');
66. }

(line 65 is printed whenever i manually save a post)

and here is line 770 of pluggables.php
770.header("Location: $location");

I've also tried reinstalling the software, but that doesn't seem to do anything. To top it all off, the 2 other Wordpress installations don't exhibit any errors at all!

[cameraman]

Looks like you're going to need to figure out where bloginfo is getting called and why - if it's about to redirect then the function shouldn't be called at that point.
You might also want to exhaustively compare the configuration details of the misbehaving one against the other two - if a reinstall didn't help and it's the same version, it's likely that it's some miniscule little configuration flag or such that's causing the different behaviour.

[wesg]

Found it. It was a plugin I had written that was breaking everything. My bad!

To all you other Wordpress users, if your blog is broken, check plugins!