I don't have the answer, but I may have some helpful info. I've done the same thing, used InfoPath Forms services + Smart Cards (I did render the forms as HTML though, I'm not sure if that's what you're doing too). But, to get this working, I did absolutely
nothing!!! To me it sounds as though you're best served by placing a support call.
Kind regards,
Margriet Bruggeman
Lois & Clark IT Services
web site: http://www.loisandclark.eu
blog: http://www.sharepointdragons.com