I tested .//hack with english patch. Going in and out of 'Area Server' re-executes the 'elfs' and going back to main menu leaves USB ram contents invalid. I don't know if plugin has to reset its state somehow or PCSX2 has to deal with that.
Hopefully this can be fixed, at least we know what's causing the issue now.
On the subject of this plugin
In Fragment, people have reported framerate drops of up to 30fps (down from 60fps) when using the plug-in.
this frame-rate drop seems to affect different people differently (some people get only 5fps drop while I get a drop of 10-15fps)
Edit: this slowdown is still present even when Logging is disabled.
The affected computers all seem to have PS/2 Keyboards rather then USB keyboards, maybe that is related?