Notes about the PIW file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The PIW file type is primarily associated with 'PI ProcessBook' by OSIsoft, Inc.. ProcessBook Displays, PI ActiveView components, and Web pages are stored and served from your Web server. The .PIW file is a container for a multiple display definitions and optionally associated VBA code.