Localhost WP for SQL->XML extraction redirecting to live URL??

I’m really frustrated here.

My ultimate goal: take a SQL backup file and extract the posts in it (200 or so) into XML format so I can import them into a redesigned site. The old site from which the posts came is no longer accessible. (Changed hosting companies.) I had already reconstructed much of the site (all of it except for the posts), so I didn’t want to backup from the SQL file into that directory, as it would require an empty root and wipe out the work I’d done.

First, I tried setting up a dev subdomain on my domain, in order to dump the backup SQL file into it and then extract the posts. But when I did, the subdomain URL (dev.mydomain.com, e.g.) resulted in a white screen of death. Tacking on wp-login.php redirected to the client’s new built site, i.e., clientURL.com/wp-login.php.

That’s weird enough to me, as we’re both using the same hosting company but we’re on completely different servers and different accounts. (I did make sure I’d logged out of both the CPanel and Dashboard for his site before I created the dev subdomain, and emptied my cache. The redirect also happened in Firefox as well as in my usual Chrome browser.)

So, one of the mods here suggested I do a local host install. I did the localhost install successfully, finally, and then tried to dump the SQL into the new database. But again, the localhost:8888 URL redirected to the client’s NEW site.

I checked the localhost site’s wp-config.php file but it was just the way I’d edited it in the localhost install process. I deleted everything and started again, just to make sure I’d hit all the steps correctly. Same result. I deleted it again and set up the localhost install again, but this time without the SQL import, so right now I’ve gota clean install of 3.3 on my machine and a SQL file I don’t seem to be able to do anything with.

My only other option here is to either myself, or hire someone to, extract all the content manually and upload 200 posts one at a time. For what should be obvious reasons, I REALLY don’t want to do that.

Can someone help? What’s going on? What did I do wrong, or fail to do? Shouldn’t it be installing the old site’s content into the new localhost site? Why is it redirecting to the active new site URL?