I got a line in fiddler2 looking like this:
ICON # status protocol host url
XXX 3 200 HTTP www.myserver.com /images/save.png
The meaning of all fiddler's icons of each session
That icon means that the session was aborted by the client, Fiddler, or the Server (see the documentation).
In the modern versions of Fiddler, right-click the session and choose Properties
. In the list of flags, there will be an X-Aborted-When
flag which shows the state of the session at the time that the abort occurred.
Fiddler changed their documentation link.
Here is the new link for all the icons:
http://docs.telerik.com/fiddler/knowledgebase/uiguide