I'm a newbie with WP and its many plugins so please be gentle with me.
I'm using NewGen Gallery and decided I wanted the more functionality that Slimbox seems to offer. After messing for a while I couldn't get Slimbox to work on my NewGen galleries so I deactivated it and deleted it.
Now the Thickbox effect of NewGen no longer works (it was before I added Slimbox) - so I assume Slimbox has left a bit of code somewhere.
I'll come back to Slimbox one day - but for the moment I just want NewGen to work with Thickbox effect (it's OK with Shutter).