Openfire kicks sessions?

we are using openfire 3.7.0

there should be more then 170000 sessions in our production environment ,but the sessions never reached 170000

when sessions reach some number ,We keep getting warning like this :

Closing session due to exception: (SOCKET, R: /x.x.x.x:10049, L: /x.x.x.x:5222, S: 0.0.0.0/0.0.0.0:5222)

org.apache.mina.filter.codec.ProtocolDecoderException: java.lang.Exception: Disallowed character (Hexdump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

at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecF ilter.java:170)

at org.apache.mina.common.support.AbstractIoFilterChain.callNextMessageReceived(Ab stractIoFilterChain.java:299)

at org.apache.mina.common.support.AbstractIoFilterChain.access$1100(AbstractIoFilt erChain.java:53)

at org.apache.mina.common.support.AbstractIoFilterChain$EntryImpl$1.messageReceive d(AbstractIoFilterChain.java:648)

……

then openfire will kick those sessions ,and sessions will never reach 170000 in openfire

do i have to do some config or someting to solve this problem ?

Anybody can help me ?

thanks