Opera beta 37, no adblock at all, 100+ tabs open all over the web, flash installed

Most of the time everything runs smooth. But:
Sometimes (very random!) when i click another link, the newly opened tab does not load.
Or it does load, but keep loading forever after displaying its contents (the little roaring circle where the tab icon should be). When this happens, i may scroll and read but i am unable to click any link on that loading-forever-page.

Fastest Workaround: close that messed'up tab, instantly re-open last closed tab per rightclick menu. There it is, everything works now.

I have no idea why this happens to me. Maybe the web just want to force me using adblock again?