Occasional End of Stream but boundary not found using MTOM

Using MTOMSample service (sample/mtom/service) to upload big amount (>1000) of files sequentially, it happens occasionally that client aborts with exception caused by "java.net.SocketTimeoutException: Read timed out." The axis2 debug log show "End of Stream but boundary not found".
In the testing environment, the client timeout was set to 10s, the size of the uploaded file is 75KB. It is also noteable that the End of Stream log on the service is shown only after > 1 minute after end of header initialisation.
The issue was reproducable on Windows XP/JRE 1.6

The issue could not be reproduced

• when the client was executed on CentOS5 JRE 1.6/1.7 or Windows Vista JRE 1.6
• when TCPMon was used to monitor soap packages (probably because this reduces throughput drastically)