Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded.The Process Explorer display consists of two sub-windows. The top window always shows a list of the currently active processes, including the names of their owning accounts, whereas the information displayed in the bottom window depends on the mode that Process Explorer is in: if it is in handle mode you’ll see the handles that the process selected in the top window has opened; if Process Explorer is in DLL mode you’ll see the DLLs and memory-mapped files that the process has loaded. Process Explorer also has a powerful search capability that will quickly show you which processes have particular handles opened or DLLs loaded.http://www.microsoft.com/technet/sysinternals/ProcessesAndThreads/ProcessExplorer.mspx

http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q838183

If you run or develop a third-party backup program that uses the Volume Shadow Copy service to back up Exchange Server 2003, you must turn on the Exchange writer in the registry.

Caution If you turn on the Exchange writer, the Backup utility cannot back up the Exchange information store and the system state at the same time. Turn on the Exchange writer only if you use a third-party backup solution, or if you want to back up the Exchange information store separately.