John, apologies for not spotting the last reply in your previous thread. It seems I no longer receive any forum notification e-mails since the last PC Advisor "upgrade".
I did a quick Google search and discovered that Process Hacker 2.31 looks like it would be a suitable alternative to the Windows Resource Monitor as it has the ability to display disk activity. I've actually used Process Hacker before and it's a useful tool that can be trusted.
Note: To enable the "Disk" tab I had to go into the "Hacker" menu -> Options -> "General" tab -> tick "Enable Plugins".