Computer will not shut down/turn off power

Well, Windows says it completed a graceful shutdown, but there's activity after that is logged. I would say something is potentially keeping the system up, but Windows has (according to Windows) shutdown properly and logged the shutdown event. I would say it could be an ACPI issue (it's the last system call before a shutdown is considered completed), however, this system is not on SP1 yet, and thus it also won't have 2775511 installed either:
Build Lab: 7600.16385.amd64fre.win7_rtm.090713-1255

I won't really say there's anything else that can be done until SP1 and then 2775511 is installed, and then all security-related updates from WU are installed. Please do the above, then take another trace if the issues continue. This is probably hardware, but you want to be on the latest and greatest and take a trace before we can really know for certain.