I am using WordPress more as a CMS than as a blogging platform - therefore using pages more. I set up my page templates for each area of the site, and initially set up some tester pages. Page templates differ only in the content of the side bar.
All was working fine until today. I edited a page's content via the WP interface, adding in an image (I was doing some CSS testing at the time). Now, that page has seemed to regress to an older page template (that's no longer on my server).
Pages that haven't been edited since they were created, but used the same template, are still displaying fine. All other pages are displaying fine - I edited a page with another template, and there were no problems.
This is not a CSS issue. I compared the source of a broken and a normal page, and there were clear differences that I did not make. I know it probably sounds weird, but the broken page seems to have regressed to an old template (of the same name, but since deleted before the new one was uploaded).
I'm hoping you can help, as I'm pretty sure it's a WP issue, and not "my fault" as such. Running 1.5.2, no plugins, no custom loops on the page.
EDIT: Oh, I should add that new pages created since the problem with the problem template also suffer from the same issues.