Application log full - pcs_perf.dll failed

NT client with Notes 6.5 multi user install - application log is filling up with the following message:

‘The Open Procedure for service ‘‘Appn’’ in DLL ‘‘pcs_perf.dll’’ failed. Performance data for this service will not be available. Status code returned is DWORD 0.’

Have searched Microsoft Technical Database though no related information - has anybody encountered this error message with ND 6.5 client?

Thanks