Seemed to have found a bug in WP 1.5.2 with Firefox (18.104.22.168)
When I open a Post with a Status of Published and then only reload the page (F5, Ctrl+R, what-have-you) the Status is changed to Draft. Repeat, status goes to Private. Repeat and status is back to Published.
I've tracked this down to being an issue with plug-ins using Quicktags. If I turn off (deactivate) those plug-ins that add a Quicktag the problem disappears.
If, on the other hand, I turn on (activate) two plugins with Qucktags the status jumps by 2, from Published to Private.
The two plug-ins in question are "Easy Post-to-Post Links" and "Terong Related Links" but I do not think this is a plug-in issue, it looks like a WP one.
Oh, this does not seem to happen under IE.