not working properly with NextGEN Gallery activated

Hello,

All went good with this theme untill I started using next gen gallery.

Weird thing is: one moment it works, the other moment not.
Some things I noticed:
– in manage widgets: not opening the Secondory Sidebar when I click the triangle
– I can click the add-media button, but nothing happens
– When I click add nextgen gallery, a popup appears, but nothing happens
– …

What helps is deactivating NextGen gallery to make it all work again.
When re-activating most of the times everything looks fine, but after a while same problems re-appear.
As said before. Sometimes I just log out (not knowing what to do to solve it) without making any changes, when I log in again, everything works just fine.

I tried exploring google for answers, and maybe it has something to do with jquery?

Does it ring a bell for someone of what I’m trying to explain (in my bad English (I’m dutch-speaking))?

Friendly regards
Ken