I'm running Windows 7 x64, and since yesterday, it's been constantly writing to the hard disk from PID 4, to no purpose. I've tried disabling updates and antivirus, but this makes no difference. Apparently cache prefetching can generate spurious disk traffic, but presumably that would be just reads, and this is specifically and almost entirely writes.
What else could be causing it? Is there a way to find out what's generating the write traffic?
Edit: not a duplicate because:
This is specifically and only writing, not reading.
The answers to the other question discuss Windows updating (which I have already tried disabling), sharing the C drive (which I'm not doing) and Autodesk software (which is not installed on this machine).
