There are several threads on Wordpress.org about this problem, but none with solutions. I just went from localhost (MAMP) to a live server (Dreamhost) and I'm getting constant 404s when submitting actions (such as changing a title) or trying to load pages in the admin (such as post/page/cpt lists).
The problem is WP is running up against memory limits (see support message below). What is the best systematic way to evaluate/troubleshoot memory use in the WP admin? Plugins tend to be implicated in this sort of problem; are there any other usual suspects?
`I've checked into why you've been receiving these 404 errors, and it seems your scripts have been getting automatically killed by our Process Watcher script due to your site(s) going over Memory limits on the shared server. 2011-07-08 08:53:59 procwatch2 INFO: Process(pid=12921, name='php5.cgi', uid=_, tty=None, cpu=17.5, rss=155764.0, vsize=264456.0): kill for total RAM 2011-07-08 08:54:19 procwatch2 INFO: Process(pid=13248, name='php5.cgi', uid=_, tty=None, cpu=29.8, rss=197348.0, vsize=305212.0): kill for total RAM 2011-07-08 08:54:40 procwatch2 INFO: Process(pid=13253, name='php5.cgi', uid=_, tty=None, cpu=39.9, rss=197376.0, vsize=305188.0): kill for total RAM`