When a radio button is hidden with "display: none" it loses its association with other radio buttons in the same group.

I've got a testcase but can't attach it because of proxy problems, but will try and attach one later. The problem revealed itself when using radio buttons with the same name across multiple tabs which were switched on and off using "display: none". A radio button appearing on a tab with display: none set, would lose it's value in favour of the radio button in the currently displayed panel.

This is probably a dup of the general bug about form elements losing state when they or their containers are set to display:none

Yes, that sounds like it. Do you have a bug number? I've got a testcase I can file against it.

*** This bug has been marked as a duplicate of 34297 ***

verifying duplicate