Analogus that is why I mentioned that I haven't really made changes to any of the settings. I'd browsed through all the options, but apart from trying a single custom font, had only looked, not made any changes.
Thanks DoctorOhh, I have just went ahead and uninstalled it, and I'll see how it is back to the default firmware over the next couple of weeks, but I've downloaded that previous version of PRS+ and might give that a try at a later date.