I just double-checked my environment variables, and I don't have any set that are related to Cyrstal Space.
I also tried copying the msjava.dll into the PlaneShift directory (thanks Durwyn), but still nothing happens when I run psclient or pssetup.
I'm the only user and Admin of this computer and the account I'm using has full administrator privileges, so I don't think permissions would be the problem.
When I run pssetup or psclient with -help in a command terminal, another terminal very quickly appears and disappears. After a lot of repeating and staring at the screen, I made out the text to say:
For pssetup.exe -help:
"Your configuration files are in... C:\Documents and Settings\username\Application Data\PlaneShift"
For psclient.exe -help:
"Your configuration files are in... C:\Documents and Settings\username\Application Data\PlaneShift
DEBUG: Sound System Software Renderer Initializing..."
I checked the c:\...\username\planeshift location (which exists), but nothing's in it.
I'll try uninstalling, redownloading, and installing again tonight.. hopefully I really did just get a bad download or something.