I have been using a local virtual machine using WMware products on a Windows 7 host that also runs Microsoft Forefront Client Security (MFCS).
MFCS is configured to schedule a scan of the disk on a nightly basis from 2am. As I have painfully noticed however, if I allow the virtual machine to be in a running state overnight, then even by 10am MFCS is still thrashing the hard disk at 100% and thus making my host machine almost unresponsive.
After an investigation, I discovered that the disk was thrashing on a VMware virtual machine “.vmem” file. This file type is apparently a backup of the virtual machine’s paging file that only exists while the virtual machine is running, or if it has crashed.
So in order to solve the problem I added “*.vmem” to the list of files to exclude when MFCS performs a scan.