I am running Windows 8.1 Update in a Parallels VM. After about 5 minutes of inactivity, a
rundll32.exe process is spawned and consumes a core.
MsMpEng.exe activity also increases. (probably due to lots of IO but I can't confirm) If I interact with the VM in any way, the
rundll32.exe immediately exits until I let it idle for another 5 minutes.
Task Manager reports that the command line is
There is no other unusual behaviour on this Windows install.
Update: Further googling has revealed a scheduled task under
Microsoft/Windows/Application Experience called
ProgramDataUpdater which seems to be the culprit. It's supposed to take care of cleanup after installing/uninstalling programs. I still haven't tracked down the core reason why it's misbehaving. Disabling it is a possible workaround but not a very good one.