I’m sure you’ve seen these signature pads in many places.  Doctor’s offices, dentists and maybe your local blood donation center.
They are USB or serial based devices and they require drivers for Windows to see them and for software to be able to talk to them.

I have a software application we use that needs the driver installed even if you aren’t using the signature pad.  To save IT management time we have this application installed on a couple of Windows Server 2003 and Server 2008 servers running terminal services.  When you install the drivers it puts them in a goofy place.  In my case I was logged in as administrator so it went to:
C:\Documents and Settings\administrator\WINDOWS\SigPlus

So, what happens when a normal user logs onto the terminal services machine?  They can’t see the sigplus.ocx dynamic link library and the application crashes.  Cool huh?
To fix this you can give everyone read access to the SigPlus folder.  There might be another way of fixing it, like moving the .ocx file and registering it in a different place, but I just tweaked the security on the folder and it worked.