The next debugging step to try is to use PSExec to execute the command as the SYSTEM account and see if that works. I generally do this by opening a CMD window as SYSTEM, then run this:
cmd.exe /C "C:\Program Files\Trend Micro\OfficeScan Client\PCCNTMon.exe" -us
To open a CMD window as SYSTEM, do this:
PSExec -accepteula -h -s CMD /K
If it works through this method, then that should match what bigfix is doing fairly closely.