IIS web server is getting crash after 3-4 hour run.

Hi, Our product has web components as a dll loaded on IIS web server. This
dll are used to server request of our product.
We are putting load on web server by firing continuous request to the server
that will served by our dll.
But IIS is getting crash after 4-5 hour, it seems that inetinfo.exe is
getting crash and restarted the web server.
To analysis this issue, we have captured logs using adplus.

adplus is dumping with unknown exception caught and following stack dump has
been observed.

00bff6ec 77c61e37 kernel32!RaiseException+0x53
00bff704 77ce3d5a rpcrt4!RpcpRaiseException+0x24
00bff714 77ce252f rpcrt4!NdrProxySendReceive+0x60
00bffafc 77ce25a6 rpcrt4!NdrClientCall2+0x206
00bffb1c 77c64f87 rpcrt4!ObjectStublessClient+0x8b
00bffb2c 776a326c rpcrt4!ObjectStubless+0xf
00bffb44 776a321f ole32!RemoteReleaseRifRefHelper+0x86
00bffb6c 776badfb ole32!RemoteReleaseRifRef+0x74
00bffbe8 776babc5 ole32!CStdMarshal::DisconnectCliIPIDs+0x245
00bffc10 776ba583 ole32!CStdMarshal::Disconnect+0x193
00bffc2c 776ba4f0 ole32!CStdIdentity::~CStdIdentity+0x89
00bffc38 776ba675 ole32!CStdIdentity::`scalar deleting destructor'+0xd
00bffc4c 7769c1e3 ole32!CStdIdentity::CInternalUnk::Release+0x6b
00bffc58 7769c1c7 ole32!ReleaseCallback+0xe
00bffc6c 7769c194 ole32!PerformCallback+0x17
00bffd04 7769c2ab ole32!CObjectContext::InternalContextCallback+0x159
00bffd5c 776f25aa ole32!CGIPTable::RevokeInterfaceFromGlobal+0x2f3
00bffda4 56f9ae81 ole32!CGIPTable::RevokeInterfaceFromGlobal+0x136
00bffdc8 56f95515 coadmin!COConnectionPoint::Terminate+0xad
00bffde8 56f96aac coadmin!CADMCOMW::Terminate+0x40

We previously used our dll on IIS and even 48 hour of continue stress run ,
we have not observed this kind of issue earlier.
This time IIS server is getting crash in just 4-5 hour of run and always we
are getting same stack trace.
I run the IIS just 3 days back and it was working fine in same configuration.
Any suggestion or any clue to finds out cause of the issue would be highly
helpful for us.