Yes, yes, very good.
Have narrowed it down a bit and it actually seems like it only happens when I link up my Cybook or my SD card (via card reader) but not when I use any other USB device like my USB memory stick or my iPod. I always use 'Safely Remove Hardware'.
Have found a website which suggests a few possible fixes, but might email Bookeen and get their take on it since I can't tinker around again till I finish work tonight.