If you tried to leave or read a comment here after about 9 PM last night, you probably saw an "Invalid Entry ID" error message. Took me long enough to figure out that Dreamhost had changed server names on me, which broke my MT.CFG file. This support forum thread gives the answer. Basically, if you're on Dreamhost and you use the Berkeley DB, you probably have a line that looks like this in your MT.CFG file:

DataSource /home/.servername/username/domain.com/blog/db

which is the UNIX path to your MT database, as reported to you by MT-CHECK.CGI. Unfortunately, that ".servername" can change without warning on you. When it does, various things can happen, including being unable to log in to Movable Type. All you need to do is to remove the "/.servername" piece, so the entry looks like this:

DataSource /home/username/domain.com/blog/db

and you'll be forevermore free of this type of glitch.

(This is the second time it's happened to me. Like an idiot, I didn't fix it properly the first time. I'm making a public confession here to shame myself into never doing that again. I'm also now swearing on a stack of O'Reilly books to upgrade to 2.64 and switch to mySQL by this weekend.)