Disables the Run, Search and Help buttons in the Start menu (they are still there, they just don't do anything)
Disables msconfig (it won't run from the command line - maybe the virus just messes with the PATH environment variable?)
Corrupts Trend Micro's main DLL so you can't do a virus scan
Disrupts the PC's ability to boot to safe mode/command prompt (it took three tries)
I uninstalled Trend Micro, replaced it with McAfee (which I get free from Comcast and was planning on switching to in May when my Trend subscription ran out), but McAfee also didn't detect the virus either on the pre-installation scan or the post-installation full scan.
McAfee tech support pointed me to a DOS-level scan which they have cleverly hidden as a separate online download (Why don't they include this with the software package?). It took about an hour to run, and fixed the problem. The report it gives is misleading - it shows how many files were scanned, how many were not infected, and even though the diff between those two numbers was 19, it showed the number of "cleaned" files as zero. But it did the trick, so I'm happy, and will be replacing Trend with McAfee on my laptop as well.