Crash report submission never works

[Matthew Paul Thomas]

Firefox 15.0.1, Ubuntu Q (and many previous versions)
Thunderbird 15.0.1, Ubuntu Q (and many previous versions)

1. Trigger a crash, for example using the "Crash me!" add-on.
2. In the crash dialog, choose to submit the error report.
3. Choose to quit or restart Firefox/Thunderbird.

What happens:
* The text "Submitting your report..." appears briefly.
* It's replaced by the text "There was a problem submitting your report."
* The dialog closes.

What should happen: The report is sent successfully.

In Firefox, <about:crashes> lists dozens of "Submitted Crash Reports", but every one of them leads to a "Crash Not Found" error page at crash-stats.mozilla.com.

Every line in ~/.mozilla/firefox/Crash Reports/submit.log (except for the first, which apparently succeeded) is of the form "[Wed 17 Aug 2011 12:43:10 BST] Crash report submission failed: Failure when receiving data from the peer".

This office does not use a proxy for its Internet connection.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.