Opus freezeing on first load

Hi folks I have been using opus for years and never had any issues with it, until now.
Basically every time I open a lister Opus freezes for a good min before it becomes active. If I open a second lister while the first is frozen it seems to open ok.

So what could cause the freeze up on first launch?

Thanks for any help

S

Crash, exit or high CPU when viewing certain directories is the best place to start.