I think I've tracked down the error some people are having, if they could re-download and try again. I also fixed a couple of other crashes that popped up so I'd re-download even if yours seems to be working.
I've added it to a zip if your having trouble downloading the exe file here: http://dl.dropbox.com/u/1867105/CK2%20Family%20Tree%20Maker.zip.
I have checked with various online virus scanners and it all comes back safe so I'm sure it is virus free. If anyone else has any virus/malware reports about it feel free to post them.
I am still getting the same error. I wonder what might be causing it, and I think it is on my side since the program seems to work fine for plenty of others.