Archived posts and 404 error

Hi, WordPress,

I recently set up a WP site for a client, and the client noticed a problem the other day that I’m hoping you can help me resolve.

The client uses the site to post a lot of images, and in each post the image clicks through to the post itself.

My client noticed that a number of posts were generating a URL containing an ‘archives’ subdirectory that doesn’t exist, and as a result some older posts are generating a 404.

I went into the Dashboard and reset the URL setting once we noticed it, and that has taken care of the problem on newer posts. However, I’ve got a couple of hundred posts that still point to the non-existent subdirectory and generate a 404.

Is there any way of re-writing the URLs on the offending posts? I’d hate to have to go in and manually adjust a couple hundred URLs – I don’t have time to do that. Is there any way to fix this, or do I have to live with it?

Any help would be appreciated. Thanks.