I want to install Exchange 5.5 on a Windows NT cluster, but cannot. I find out that the reason is when install Exchange 5.5, some changes must happen with files perfh009.dat and perfc009.dat (in %SystemRoot%/system32). But I cannot do anything about these files (I have the administrator right) because they are used by another program. How can I know which program is using them ? Or what can I do so that I can change these files (rename, for example). Thank you so much. Ha.