EMWProf fails with error in the log file such as the example below:
18.11.2009 09:55:26 Core [Trace] Moving original OST file D:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Outlook\username.ost into D:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Outlook\emw_username.ost.
Error code: 0x00000020
Description: The process cannot access the file because it is being used by another process
This error means that the OST file is locked & the tool cannot gain exclusive access.
Typical cause would be that Outlook is launched before EMWProf has completed, but it is also possible that it could be some third-party utility accessing the file such as anti-virus, or anti-spyware scanners such as those sometimes included in Microsoft updates.
To confirm which process is locking the file Process Monitor could be used (http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx).