Ah the challenge of trying to come up with keywords to describe (and therefore search for) an odd, but simple issue...
This event manifests itself in other admin tasks...
The one I have in front of me, and therefore the one I remember is this:
WPMU 2.3.3 PHP 5.2.5 MySQL 5.0.45 Apache 1.3x
Using subdomains, wildcard DNS enabled etc.
Logged in as an admin on a subblog, adding a new category:
When I hit the "Add Category" button, the page refreshes, the category is not added (and the add form is still populated with my data) and in a pink background-colored box/div, the serialized (think mobile device, one long narrow page) contents of the subblog's home page is displayed. I assume that some sort of error message was piped to the screen but something gets lost in translation. No server errors in the log.
I read a few threads about hardened PHP modules and have a ticket in with my host. They don't like these sorts of questions!
Anyone see the obvious?
Thanks.