One add turns off other

[vedran-milic]

I have header add which is always visible on the page, and another add inside my tabs. It's on the first tab and it's initially visible.
When I go to the second tab, and then return to the first tab, header add disapears.
It's like reinitialization of add inside tab disables the add in the header.
Header add elements receives display: none style.
Has anyone encountered this problem?