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Store.exe on Backend Exchange 100% CPU causes Front End W3WP.exe 100% CPU and requires IIS reset to release

Our Exchange Environment has a Front End and Backend Exchange 2003 SP2 on Server 2k3 Standard. All Has been well until 1 week ago. No changes were made. etc.
We have since ran updates on both systems and applied the following MS patches as a result of our issue:
KB941439, KB970103, KB920760

Our Backend Server will crank up the CPU on Store.exe every 5-15 minutes or so (no set time has been noticed). The Server Handles the processing and returnes to normal in 1-2 minutes. When the Store.exe on the backend server returns to normal, the w3wp.exe on the frontend server spikes to 100% CPU and will not release. We then run IISreset.

We have tried with and without our current Symantec AV configuration with no changes.
Watch Question

How many instances of the w3wp.exe would be running in the Task Manager.

Do you host any other Web Sites on the IIS for the Front End Server apart from the default web site.

Do you get any Event IDs related to this in the Front End Server or Back End Server.


There are two instances running. one System and One Network. the System one is causing the havoc.
Apps are OWA\Active Sync and only the default Exchange website are running on this machine.
There are no Event ID's associated with the processor maxing out.

A side note is that these two machines are VM's in a VSphere 4 update 1 environment. Microsoft refused to assist with this one.
Will have a call with VMWare in the morning to confirm the CPU configurations, but all has been running well and there were no changes made to either system
Unfortunately VM Ware with Exchange 2003 on it is not supported by Microsoft.

There might be a memory leak in the Front End Server. Try stopping the SMTP Service alone and see if there is a Spike on Front End Server.
Aparently there are multiple issues, not just this one.
After Upgrading VMHardware, Allotting additional processing power to the VM's, Updating all of the OS's on the Exchange Servers the performance issue has been resolved, however due to the updates there is one final issue presenting itself, another question to be opened.