I, too, have this issue. I have disabled all plugins but akismet, feedburner and wp-cache. Those three are running the latest version and the auto-save timer still loops too quickly. When I disable them, the bug still takes place.
Your server is returning this for the mainstyle.css URL:
<!DOCTYPE HTML PUBLIC “-//IETF//DTD HTML 2.0//EN”>
<HTML><HEAD>
<TITLE>404 Not Found</TITLE>
</HEAD><BODY>
<H1>Not Found</H1>
The requested URL /blog/2005/07/stylesheets/mainstyle.css was not found on this server.<P>
<P>Additionally, a 404 Not Found
error was encountered while trying to use an ErrorDocument to handle the request.
<HR>
<ADDRESS>Apache/1.3.33 Server at http://www.keviv.net Port 80</ADDRESS>
</BODY></HTML>
Therefore you need to check your URL.
