Redirection after registration is failing

I seriously doubt that this is a logintoboggan bug but I have to start somewhere. I have custom redirections in place for both registration and confirmation, I have enabled "set password" and "immediate login", created an appropriate role for the time in purgatory and all works very well except for the registration redirection. The confirmation redirection works as advertised but any value in the registration redirection is ignored and the user is redirected to the front page with an argument appended to the URL, like

/?544872296=1

the number is different each time and seems random, certainly not sequential. I see a similar appendage to some other system redirection, like for instance the VBO interface to content

/admin/content/node2

where return from an edit link sees a similar value as above appended which makes a subsequent return from a new "edit" fail exactly as logintoboggan does. Thus I assume that logintoboggan is a victim rather than the culprit.

But, I'm hoping that despite the lack of anything obvious in the issues list, you might have seen this problem before and can assist me in troubleshooting further. Where as the Views Bulk Operations (node2) error above is annoying, it only affects administrators, this redirection failure only affects new users, the worst group to provide a negative experience to!

Any help including some direction as to a more appropriate place to ask the question, is appreciated.