linux subversion checkout hangs since server was virtualized

Hi all,
 
just migrated our subversion server from physical machine into a VM guest (VM
host is citrix xen server).
 
Complete access from Windows clients is still fine now.
Update, Log and Commit are fine from linux command line as well, but not fresh
checkouts. 
 
The hanging client is a 1.6.12 on Fedora. The server has v1.6.15
The hanging client was fine, as long as Subversion was served from the old
physical host.
 
At first, I thought that following error messages are related as they occur when
the problem occurs, however, just found out that these errors already occurred
in the past as well ... without any clients hanging:
Error writing base64 data: APR does not understand this error code  [500,
#620018]
[client 172.17.4.191]
A failure occurred while driving the update report editor  [500, #620018]
[client 172.17.4.191]
Provider encountered an error while streaming a REPORT response.  [500, #0]
[client 172.17.4.191]
Error writing base64 data: APR does not understand this error code  [500,
#620018][client x.x.x.x]
A failure occurred while driving the update report editor  [500,
#620018][client x.x.x.x]
Provider encountered an error while streaming a REPORT response.  [500,
#0][client x.x.x.x]  
Appreciate any hints/ideas. Would a net traffic capture be of help?
 
Regards,
Joerg.
 
 
 
The end of an strace wasn't particularly enlightening either ... whenever a
checkout hangs a file is opened without being written/closed and it keeps
polling/receiving ...

open("firmware/dam_bin/.systemdata/images/.svn/tmp/text-base/ru2_border.png.svn-base",
O_WRONLY|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0666) = 8
fcntl64(8, F_GETFD)                     = 0x1 (flags FD_CLOEXEC)
fcntl64(8, F_SETFD, FD_CLOEXEC)         = 0
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4, revents=POLLIN}])
recv(4, "\27\3\1\1\20", 5, 0)           = 5
recv(4, "T\n\212\1\253\202\2254\317%E\2753\320\3=\355\256g\37
b\205\22676\274\356z\221=\270"..., 271, 0) = 271
recv(4, "Q", 1, MSG_PEEK)               = 1
gettimeofday({1296739105, 955975}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
gettimeofday({1296739105, 956556}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
recv(4, "Q", 1, 0)                      = 1
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4, revents=POLLIN}])
recv(4, "\27\3\1\0 ", 5, 0)             = 5
recv(4,
"\215\363{@\254\357]\325h\230\2448\264\373\346\233\\\312\366\1\262ra\20\5\244\253+o\336\376",
31, 0) = 31
recv(4, "\223", 1, MSG_PEEK)            = 1
gettimeofday({1296739105, 957482}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
gettimeofday({1296739105, 957841}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
recv(4, "\223", 1, 0)                   = 1
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4, revents=POLLIN}])
recv(4, "\27\3\1\0 ", 5, 0)             = 5
recv(4,
"6\317\230\0\274\307I1\355\354\235\250C>E\213v\373\177^@G\3278\216\333\203\370\23\5|",
31, 0) = 31
recv(4, "Z", 1, MSG_PEEK)               = 1
gettimeofday({1296739105, 958722}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
gettimeofday({1296739105, 959114}, NULL) = 0
getrusage(RUSAGE_SELF, {ru_utime={0, 456028}, ru_stime={0, 840052}, ...}) = 0
time(NULL)                              = 1296739105
times({tms_utime=45, tms_stime=84, tms_cutime=0, tms_cstime=0}) = 1718723967
recv(4, "Z", 1, 0)                      = 1
poll([{fd=4, events=POLLIN}], 1, 3600000) = 1 ([{fd=4, revents=POLLIN}])
recv(4, "\27\3\1\37P", 5, 0)            = 5
recv(4,
"\347\254\361\244x\270m\265\350\234\177r\23RG\240[\336?\235\32\0\200\37\224[\36#c\327\n\263"...,
8015, 0) = 935
recv(4,  <unfinished ...>
Received on 2011-02-07 16:04:56 CET