Just to make sure everything installed correctly, does your PlasmaClient installation directory look like this?
Beyond that, you can try grabbing
depends.exe, which will tell you if you're missing any DLLs that it needs- it's always possible that I made a mistake when I tried to sort out the dependencies and bundle them all.
EDIT: one other thing that *might* make a difference is your Windows version - it should work fine on 32- and 64-bit XP, Vista, and 7, but obviously I'm only able to personally test on a subset of those. I have no idea if it will work on Windows 2000, and it actually might not - my build targets XP and newer.
IanWatson, your problem could be login related. You have to be very careful about having your email in the right case (meaning that
[email protected] won't work if you made your account with
[email protected]), it will refuse an email/login because of that. I think the MOUL login is more forgiving.