About Hardware and softare inventory problem

hi,
the hardware and software inventory don't function well in one of our primary site, i can only find several client scanned.
even on the sccm server, when i start the Resource Explorer, there is nothing there, no hardware, no software, no last scan.

and i do configure the hardware and software inventory agent to run every one day.

when i check the event, i find the WinMgmt 63 error.
A provider, PolicyAgentInstanceProvider, has been registered in the WMI namespace, root\ccm\Policy\S_1_5_21_3385730835_3961786211_3716683657_9724, to use the LocalSystem account.  This account is privileged and the provider may cause a security violation if it does not correctly impersonate user requests.

anyone can help?

thanks

Rain