Admin bar missing and add/edit Posts gives Error 324

I posted this over in the install forum, but we couldn’t figure it out there, and it seemed to me that this might be a better home for it anyway:

This is a clean install, downloaded yesterday(March 7) via wget from www.ads-software.com, no plugins, running twenty eleven (also tried with twenty ten, same issues).

First, the admin bar isn’t showing up, and the php error log is showing:
Invalid argument supplied for foreach() in [snip]/wp-includes/class-wp-admin-bar.php on line 343

Next, updating/adding posts gives a “Error 324 (net::ERR_EMPTY_RESPONSE): The server closed the connection without sending any data.” but still saves the edit/new post, and a reload of the error page brings you right back where you should be. Oddly, Pages work fine, it’s only Posts that show this behavior.

On a related note, quick update of Posts doesn’t work at all, clicking on “Update” causes the progress animation to start up and continue indefinitely.

Other notes:
this is the second install (from a completely new download, new directory structure, new db) I’ve done on this host, both showed the same exact issues. Also, I’m not really seeing anything helpful in the error logs.

I have tried using IE/Firefox, and have the same issues there.

All other content submission works fine, it’s just Posts that’re giving the error.

This is the first wordpress install I’ve ever done on this particular server and I’m guessing it’s something in the setup of the server, but don’t really know where to start, and google/searching the forums haven’t helped.