It would be very handy if Firefox 2 users installed the prerelease version of Dephormation to capture a log of redirects during the sign up process.
Download from here;
http://www.dephormation.org.uk/prere...phormation.xpi
(nb right click, save as, drag into Firefox to install)
I feel like I'm briefing Christians being thrown to the lions. Here's a checklist. Watch out for the one with sharper teeth. Don't carry a ham sandwich in your pocket. Don't be the slowest runner etc.
PS; you need to be sure you only enable the log file output feature during sign up (don't run with the 'disable Phorm'/'randomise Phorm UID' features on, for obvious reasons 
).