Error updating working copy to 1.7

Right-clicked on working copy folder, and selected "SVN Upgrade working
copy". I clicked "Upgrade the working copy" in the confirmation dialog, the
process starts, then the following exception is generated:

---------------------------
Subversion Exception!
---------------------------
Subversion encountered a serious problem.
Please take the time to report this on the Subversion mailing list
(users_at_subversion.apache.org)
with as much information as possible about what
you were trying to do.
But please first search the mailing list archives for the error message
to avoid reporting the same problem repeatedly.
You can find the mailing list archives at
http://subversion.apache.org/mailing-lists.html

Subversion reported the following
(you can copy the content of this dialog
to the clipboard using Ctrl-C):

In file
 'D:\Development\SVN\Releases\TortoiseSVN-1.7.0\ext\subversion\subversion\libsvn_wc\entries.c'
 line 1935: assertion failed (svn_checksum_match(entry_md5_checksum,
 found_md5_checksum))
---------------------------
OK
---------------------------

I'm running Windows 7 SP1 (Version 6.1, Build 7601) 64-bit.

-- 
Chris Gundersen
Founder and President, Techometry
http://www.techometry.com/
Phone: (615) 669-3380
Email: chrisg_at_techometry.com