Hey guys, I am having the same problem and it's been driving me mad. I, too, found that Dutch site and have been running SPSS as root to avoid having to kill off my user account and open another, which would be a nightmare.
One thing you can do, though, is make that command into an executable shell script, so you don't have to remember it every time.
Just open a text editor that actually saves files as just plain text (I heartily recommend TextWrangler), and type this in:
#!/bin/sh
sudo /Applications/IBM/SPSS/Statistics/21/SPSSStatistics.app/Contents/MacOS/stats
--All that's doing is sending the Dutch guy's little command to the terminal.
Then save it as whatever (I called mine "Launch SPSS"), but instead of a .txt or .sh extension, make it .command, as below:
Launch SPSS.command
So now OSX knows it's a shell script, but we want it to run on a double-click, because we're lazy.
Open up Terminal and type:
chmod +x [Then drag the file to the Terminal window and it'll put in the path automatically!]
And hit return. It'll ask for your password.
So now when you want to start up SPSS, you double-click that script, it'll open the Terminal, asking for your password (since you are telling the computer to run that file as root, same as if you typed the command), type in your password, and SPSS will launch.
Then you just quit Terminal.
I admit it still *****, and wouldn't happen if IBM didn't take some sick glee in selling software for $2000 that almost never works when you need it, but it's better than trying to type all that every time.
Also, if you've had it with IBM's prices, check out the RKWard GUI for R. It's getting really good, and basically makes R work like SPSS for a lot of things. The only reason I'm using SPSS is that I'm teaching a course and learned my lesson about trying to get a room full of undergrads to install open-source software. I swear there were tears in some kids' eyes when the package manager came up. For my own work, I've been on RKWard for a year now.
Good luck!