PaMdora

When I write my own htaccess file, it goes to 404 also, but think I’ve figured it out.

When the pretty permalinks are on in the main blog, the password protect option goes to 404. When they are off in the main blog, password protect works fine.

It doesn’t matter how the sub-blog permalinks are set. Works either way.

Thanks! I’ll try it.

I already have an htaccess file, so I’m assuming that I add the password code to it – does it matter if above or below the permalinks code?

You’re right. I had forgotten to deactivate plugins on the last two upgrades.
I took them off, and did manual upgrade. Now everything’s working. Thanks!