So far I haven’t found anyone on the net with a similar problem, neither some information that could point me to a possible solution. Seems like a bug to me. In the meantime we’ll just have to disable the use of swfobject.
Anyhow, it seems that Mircosoft will release an IE update soon, changing the way ActiveX is handled like it was back in 2006. It’s about time and they should never have changed it in the first place.