Merge replication fail to sync!!! HELP!!!

Basic setup is in such a way:
1 Server (sql 2008 std) - 7 Workstations (sql 2008 exp)

For each workstation, there will be 2 publication on the server for it.
So far 6 workstations are able to sync properly using windows synchronization manager to do pull subscription.

With the exception of 1 workstation, while 1 publication was able to sync.
Another failed with the following 4 errors in the replication monitor:

1) Unable to retry the command. The merge process could not add retry information at the Publisher on tempdb. This may be due to too much activity on tempdb. Restart the synchronization when activity on tempdb has decreased. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147201015)
- i have checked the database at 1.6gb, tempdb at ~600mb and distribution at ~80mb.
- ram is running with extra physical ram.

2) Error converting data type bigint to int (Source: MSSQLServer, Error number: 8114)

3) The merge process could not replicate or more INSERT statements to the 'Publisher'. A stored procedure failed to execute. Troubleshoot by using SQL Profiler. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200990)

4) The process was successfully stopped. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200999)


Any help to resolve this problem would be appreciated, as it is very urgent and important!!!
Thanks!

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