WordPress MU

Recently I've noticed that my blogs are being created with the domain "domain.tld" instead of my actual domain. This is something that has started happening recently.

There has been no changes made to the site or server since it's worked.

What could be causing the issue. I thought maybe there was a setting that inadvertently got changed somewhere.. I could not find anything. PLEASE HELP!!!

Are they legit blogs from legit users? I smell spam/splogs. As in, someone is autocreating blogs and giving it that URL.

I had the same error, at first it was domain.tld.com
I'm the only one creating the subdomains as its a rather new site and it worked fine for about a few days till 2 to 3 days ago.

domain.tldBASEsiteupdate/ (username is siteupdate)
domain.tldBASEupdate/
domain.tldBASEtest1/
domain.tldBASEfasddf/ (I started just typing in stuff like fasddf for username)

Then after replacing .htaccess with the default htaccess file (and using the line 'RewriteBase /' instead of the default line ) it became.

angloindianblogs.comBASEss2007/
angloindianblogs.comBASEpackage50tol/ (username package 50tol)
angloindianblogs.comBASElpackagetompackage/ (username package lpackagetompackage)

It started about 2-3 days ago, and I've installed about 10 modules and not sure which modules required me to manually change key files. I remember adding 2 captcha plug ins wpmu-signup-captcha and WP Captcha 1.0 for wordpress mu 1.2.4 - 1.2.5a

pgesystems can you recall which modules you added after the new subdomain registration errors started?