Carl said:
David-thanks for your input. You pointed me at Vista's firewall and that
enabled me to locate the program that was causing so much disk activity
involving wfpdiag.etl.
I had installed a program from Shinx Software called Vista Firewall
Control that allows management of the firewall via a simple GUI. It
installs as a system service. Once I disabled the service and rebooted,
the disk activity ceased.
Ahh, now that you mention it, I thought I had seen that file being accessed
at some point on this system but just couldn't remember the specifics since
it was happened some time ago. But yes I had installed Vista Firewall
Control some time ago, and the reason I removed it was this constant file
access.
Glad it's sorted now.