Specific Permalinks Give 404 Error

I’m having the strangest problem with some =specific= Permalinks.

It started when I started using the HTML Import plug-in http://sillybean.net/code/wordpress/html-import/ to import 400 static html pages into WP Posts. The posts imported OK as -drafts- BUT there is something terribly wrong with the permalinks and I can’t figure it out.

I could edit the posts just fine in the WP admin, but again, if I would go to ‘View’ the post… even if I use the shortcode URI, I get a 404… it would just redirect to the postname permalink and then throws a 404.

Also, I checked the .htaccess and it’s the std one you see in the Codex post on Permalinks.

Here’s what I know.

1. All the posts and pages I’ve written (not imported) work fine.

2. All the posts I imported with HTML Import only worked with the default structure (?p=3321)… when I try to use ‘pretty permalinks’ these imported posts throw a 404.

3. BUT if I edited the permalink of an imported post–for example changing one char—it then WORKS. However if I change it back to what it originally used (which is usually what I want), it again fails.

So… it seems as though the permalinks are somehow being ‘reserved’.. ie. they’re being used by some draft or trash version of a post I can’t ‘see’?

In desperation, I backed up the db, used the WP Exporter to back up the posts, then dropped the WP_Posts table. I then re-imported.

OK, so all the HTML Imported posts now ‘work’. BUT if I change the permalink, it fails again… ie. I acessing the page using a postname permalink fails. And again: switching back to the old ?p=1234 format fixes the issue.

DRIVING ME NUTS!

There’s gotta be some rewrite going on that’s interfering, right? How to troubleshoot?

TIA,

—JC