Error by Update/Checkout: Could not read chunk size

Hello,

we have some problems with Update & Checkout commands with our server. It brings a request failed message (see screenshot) and stops the command.
When doing immediately afterwards the same command, there are no more files transfered and the command finish the command.
We have this problem from different clients (TSVN 1.4.6 / 1.4.8, SVN 1.4.6) from time to time. Running "svnadmin verify" on the server detects no errors.

Searching on the internet I didn't find a solution for my problem.
I turned the on-acess virusscanner off on both sides, server and client.
I tried to use <Location /svn> instead of <Location /svn/> (see http://www.nabble.com/Chunk-Size-Error-td16504073.html or http://svn.haxx.se/users/archive-2005-02/0751.shtml )

Server:

Windows Server 2003 SP2 English
Apache/2.2.8 (Win32) DAV/2 mod_ssl/2.2.8 OpenSSL/0.9.8g mod_auth_sspi/1.0.4 SVN/1.4.6 mod_aspdotnet/2.2

Apache Configuration:

# Subversion
RedirectMatch ^(/svn)$ $1/
<Location /svn/>

  DAV svn
  # any /svn/foo URL will map to a repository C:/svn/foo
  # I've only got it working using SVNPath!!
  SVNParentPath D:/SCM/SVN/data
  SVNListParentPath On
  AuthType SSPI
  AuthName "Subversion (Einloggen als 'EU\Benutzername')"
  AuthzSVNAccessFile D:/SCM/SVN/config/svnaccessfile.conf
# Require valid-user
  Require group PFVM-DEV1\SCM_Administratoren EU\Nec-AllUser EU\Nec-Rnd-Externe
  SSPIAuth On
  SSPIAuthoritative on
  SSPIDomain <domaincontroller>
  SSPIOfferBasic on
  SSPIOfferSSPI off
  SSPIBasicPreferred On
  SSPIOmitDomain on
  SSPIUsernameCase lower
  SSLRequireSSL
</Location>

CustomLog logs/svn_logfile "%t %u %{SVN-ACTION}e" env=SVN-ACTION

SVN Log:

[19/May/2008:17:09:26 +0200] jlinnenkohl update '/trunk'

Apache Log:

10.0.10.142 - - [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/trunk HTTP/1.1" 401 401
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/trunk HTTP/1.1" 207 692
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/!svn/vcc/default HTTP/1.1" 207 407
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/!svn/bln/1765 HTTP/1.1" 207 464
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/trunk HTTP/1.1" 207 692
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/!svn/vcc/default HTTP/1.1" 207 407
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/!svn/bln/1765 HTTP/1.1" 207 464
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "PROPFIND /svn/BestFit/trunk HTTP/1.1" 207 692
10.0.10.142 - jlinnenkohl [19/May/2008:17:09:26 +0200] "REPORT /svn/BestFit/!svn/vcc/default HTTP/1.1" 200 98460

Apache Error Log: Nothing

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