Hey,
Thanks for your reply.
Okay, so, firstly I have no C:\Program Files (x86)\Reference Assemblies\Microsoft\WindowsPowerShell directory. I have C:\Program Files\Reference Assemblies\Microsoft, with only one subdirectory, called Framework, and with no System.Management.Automation.dll to be found at all.
There are three copies of System.Management.Automation.dll on my machine, one in the PC Monitor directory, one in a sub-directory of C:\windows\assembly and one in c:\windows\winsxs.
Opening up the trace.log file, it contains one line, which is as follows:
20/12/2012, 22:04:57.212: [service] Received Request Run PowerShell command 'ls' from device Id: 'a4f38f4908c67b6'
There are no errors in there at all; I've run several commands to be sure.