Merge replication - sync failed (after high number of rows updated)

Hi MSDN and all helpers on this forum.

I'm facing a new problem with SQL Merge replication. (yes, a new one , even if i'm working with merge replication since years, this error is the first one...)

Topology : SQL 2008 64bits on a datacenter box. Merge replication, using web (replisapi.dll).
Subscriber : sql 2008 express on a win 2003 32 bits.

Sync is started using RMO on the subscriber.

I update a lot of records (40.000) on one table (that has +- 40 fields).

When I try to sync from the subscriber, i see the w3p (replisapi) memory growing (up to 400 MB).

Then, after 1 min i get an error on my subscriber.

I enabled the log on subscriber : here is what i've got :

2012-04-16 11:34:43.109 Downloaded a total of 3100 chunks.
2012-04-16 11:34:47.328 OLE DB Subscriber 'subscriber': {call sys.sp_MSadd_merge_history90 (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)}
2012-04-16 11:34:47.421 The response message was received from 'https://serverweb/SQLReplication/replisapi.dll' and is being processed.
2012-04-16 11:34:47.468 OLE DB Subscriber 'subscriber': {call sys.sp_MSadd_merge_history90 (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)}
2012-04-16 11:34:47.578 The format of a message during Web synchronization was invalid. Ensure that replication components are properly configured at the Web server.
2012-04-16 11:34:47.687 Disconnecting from OLE DB Subscriber 'subscriber'
2012-04-16 11:34:47.734 Disconnecting from OLE DB Subscriber 'subscriber'
2012-04-16 11:34:47.781 Disconnecting from OLE DB  'subscriber'
2012-04-16 11:34:47.843 Disconnecting from OLE DB  'subscriber'

If I check the log on the replisapi.dll i've got

MODULE NAME                   , UTC DateTime           ,  TID,  LINE, SEV, MESSAGE
-----------                   , ------------           ,  ---,  ----, ---, -------
CReplDebugLog                 , 2012/04/16 11:29:39.992, 3316,   287,  S1, Starting log file.
CHttpListener                 , 2012/04/16 11:29:43.227, 3316,   258,  S2, INFO: Exchange ID = 31F28F1A-00B8-49ED-9F7F-19F5D7307C8A.
CHttpListener                 , 2012/04/16 11:30:04.804, 3568,  1687,  S2, INFO: IsClientConnected: TRUE
CHttpListener                 , 2012/04/16 11:30:47.944, 3316,  2755,  S1, ERROR: ErrNo = 0x80070715, ErrSrc = <null>, ErrType = 10, ErrStr = The process could not write the response message due to OS error 995.
CHttpListener                 , 2012/04/16 11:30:47.944, 3316,  1271,  S1, ERROR: ErrNo = 0x80070715, ErrSrc = <null>, ErrType = 10, ErrStr = The processing of the response message failed.

If I check on SQL Replication monitor (sql box), i see nothing special...

Any idea ?