Problem with memoir and biblatex together

For no reason I can understand, I can't compile the following using TexLive 2011:

\documentclass[12pt,a4paper]{memoir}

\usepackage{biblatex}

\bibliography{mnwe-thesis}
\begin{document}

Following Serre\cite{serre_Trees}

\end{document}


with the .bib file mnwe-thesis.bib:

@Book{ serre_Trees,
series = "Springer Monographs in Mathematics",
title = "Trees",
isbn = "3-540-44237-5",
url = "http://www.ams.org/mathscinet-getitem?mr=1954121",
publisher = "{Springer-Verlag}",
author = "{Jean-Pierre} Serre",
year = "2003",
note = "Translated from the French original by John Stillwell, Corrected 2nd   printing of the 1980 English translation"
}


The error I'm getting is:

.
.
.
(./mnwe.bbl)
Package biblatex Info: Reference section=0 on input line 6.
Package biblatex Info: Reference segment=0 on input line 6.

! Undefined control sequence.
\biburlsetup ->\Urlmuskip
=0mu plus 3mu\relax \mathchardef \UrlBigBreakPenal...
l.13 Following Serre\cite{serre_Trees}


I'm highly surprised since memoir is listed specifically as a compatible package in the biblatex docs.

Edit:

Changing the documentclass to article doesn't help. I also added \listfiles after \begin{document}. The output is here: http://pastebin.com/9dMgNzpz.

-
Try adding \usepackage{url} –  egreg Dec 15 '11 at 17:56
I can't reproduce this, neither with biber nor bibtex. What versions of the two packages are you using and is really caused by memoir. What happens with one of the standard classes? –  Simifilm Dec 15 '11 at 17:56
This works fine for me; can you add \listfiles immediately before your \begin{document} and post the output –  cmhughes Dec 15 '11 at 18:00
Did you delete the .bbl auxiliary file? Perhaps there's a "bad" .bbl file from a previous run and this is causing the problem. –  Gonzalo Medina Dec 15 '11 at 18:00
The current error is from an outdated url package. Your version is 1999/03/02 ver 1.4, while the most recent on CTAN is 2006/04/12 ver 3.3 which defines \Urlmuskip. –  Werner Dec 15 '11 at 18:26

The current error is from an outdated url package. Your version is 1999/03/02 ver 1.4, while the most recent on CTAN is 2006/04/12 ver 3.3 which defines \Urlmuskip.
It appears to be in texmf-local, so perhaps something old overriding the newer one in TeXLive 2011. –  qubyte Dec 15 '11 at 18:29