It should be noted that no registry entries are required to have MxO function. In fact I have 5 installs of the game for my various needs and as it turns out none of them were installed on the computer I primarly test with.
You should be able to simply copy the entire install to a different location, make a new short cut to your Launcher.exe file and run the game. (or change the shortcut you originally used if you feel comfortable doing so.)
I would try doing a full scan of the game's files including the launcher to verify that none of the files were copied badly. This has only happened to me on a couple of circumstances.
All this is predicated on the assumtion you are using XP and not Vista. (which has its own bag of hammers you have to work through)
Right click the launcher.exe file and click properties.
Look for an 'Unblock' button. If you see one, click it. Windows firewall may be actively blocking it.