Cmdagent generating massive numbers of error files

I have been trying to fix up some software (Sony PMB) which inexplicably stopped working yesterday, and have been trying all sorts of things to sort it out. At one point I disabled the Firewall, HIPS and antivirus components to see if they were interfering, but once I established they were not I switched them all back on.

At some point (could have been before or after this), cmdagent.exe started generating logs, which I had set to move to “my documents” in case there was a problem. But 50 000 of them filled my C: drive and that was a problem in its own right! I deleted them, but it was then generating close to 100 every minute - each 20 MB.

I have turned off the move feature, and so I guess about 200 instances of cmdagent are writing at between 1 and 350 KB/s (based on Windows’ Resource Monitor) but now to the same file, deleting it every time it reaches 20 MB.

However, I allowed some more to be moved for a brief period, and when viewed all were empty - no events of any type were recorded in each 20 MB file.

Total CPU usage by cmdagent.exe (shown as a single instance in Task Manager) is minimal (approx <1%).

Any ideas as to what the problem is and how to stop it?