Ive just signed up a new tempry account and went through all of the steps to successfuly create an account without a hitch.
All i can think is that the xleague site and the myleague sites are not talking on your browsers properly, you could try bypassing the xleague site by going directly to.
http://www.myleague.com/teamrs3/ as soon as step 2 is done you should get an email with an activation key, this sometimes goes into your junk folder as your email server may tag it as spam.
For step 3 uncheck all of the promotional stuff as ladderbux are useless.
Im at work at the moment, but please let me know if you are still having troubles.