rsync hangs on a big file

[Tony Gaddis]

I am running rsync 2.6.4 and the source file to be copied is 35.6GB and 
the previous old version target file is 25.2GB. Running with logging at 
vvv, the last output before the process appears to hang is:

match at 25174423560 last_match=25174423560 j=158665 len=158664 n=0
match at 25174582224 last_match=25174582224 j=158666 len=158664 n=0
match at 25175091312 last_match=25174904728 j=85502 len=158664 n=186584

FYI, ls -l of the target file is:
-rwxrw-rw-    1 smbuser  smbusers25174885376 Nov  8 04:09 
InformationStore.bkf

the source machine appears to be waiting for more data and the target 
machine must think it is done with the check sum process, both systems 
show the rsync tasks taking 0% of the CPU.

Any ideas, (and yes I am thinking about how to use smaller files :)).

Thanks
Tony Gaddis