Are you running as a Limited User? How about UAC on the system? Did you install the HDTracks downloader with MC still running, perhaps?
I just tested. I downloaded the current HDTracks downloader, and installed it (19.0.60, as you mentioned). Then, I made sure to close out of Media Center (including the Library Server in the tray) and installed it. Note: I don't know if this makes a difference, but since they're both built upon some of the same shared components, this seemed like a good idea.
Anyhow... It installed and worked. Then, I closed it, and opened MC. MC did raise the UAC prompt then (as it does when you run MC18 and then try to run MC19 again, for example), but then after I approved it, MC loaded and worked fine.
Then, I tried, with MC still open, to re-open the HDTracks downloader, and this also worked fine.
So... I'm thinking the fact that it can't register JRTools dll (which is what it seems like is happening, and what caused that UAC prompt on my system) is the culprit.
I'd uninstall the HDTracks downloader. Then, for good measure, install the latest build of MC (over top, even if you already have it). Then, with MC closed completely, install the HD Tracks downloader. That might be all it takes, but post back if there's anything odd about your setup.