[Bazooka_Joe]

If you are going to screw with the registy, make sure you make a backup of it first. (Registry>Export Registry File)

Let's try this first though. Go here:

http://www.3dgamers.com/games/medalofhonor/

and download the US/UK patch, 5th file down. Install it, even if you already have it. Then, try to install Spearhead again. If this dosen't work, you can try what Mieserbeutel said.

If all else fails, do a fresh install of MOH:

http://mohaa.xgshosting.com/joe/installguide.htm