Ati 3870 Crossfire crash on multiple monitors

Hy all, i have an Dell Dimension XPS 730 with 2 Ati Radeon 3870 Video cards. My problem is:
With 2 monitors works fine, when i connect an additional monitor ( 3-rd ) and i choose extend monitor... windows Vista crashes ( blue screen , memory dumping ).
I tried with the crossfire cable between the 2 video cards, and without. Same story.

I'm noob in crossfire / sli things.

10x in advance.

Crossfire only supports 2 displays (and they have to be connected to the primary card). The third shouldnt even work.. but it makes sence CF crashes if it does..

To use 3 displays corssfire has to be disabled, it should work then..

Make sure you have the latest drivers isntalled.

I assur you that Crossfire will onyl allow 2 monitors. They must be pluggted into the primary card. Despite knowing this first hand having owned a couple crossfire rigs, you can loko it up on wiki easily enough.

Now, as for using a 3rd monitor with the same two cards, that you can do.. but you must disable crossfire first, when that is done the second card will act on its own and allow you to use its outputs. You can set up a profile to switch quickly. But make sure the drivers are up to date or crossfire enable/disable can be buggy.

Problem solved, i've updated the driver...same story, i changed the second video card, and the 3-rd monitor worked just fine.
I want to thank tom's hardware and daedalus for support and for the fast reply.