Losing post text–also cannot edit after saving, cannot edit in HTML

I’m having three problems, which may or may not be related:

(1) When I save or publish, I lose anything I typed into the “post body” window. Title gets saved and even published properly, but not the post body.

(2) After a post has been saved, if I go to edit it, there isn’t even a text box for me to put the post body in.

(3) If I try to switch to editing in HTML, I get a “page not found” message.

The fix involving .htaccess described in the link below has not helped me:

http://ww.wp.xz.cn/support/topic/117847?replies=15

In case it matters, I set up WordPress using the autoinstall feature of StartLogic, a hosting service. I am currently using the NoScript Firefox plugin, in order to avoid the problem of a hyperactive autosave feature. The problems described above largely predate use of NoScript, though I think at first the button for switching to HTML editing just plain wasn’t working. Not sure if that changed right as I added NoScript or not–didn’t do a careful test.