Thanks again, Ironass.
I have repeatedly tried to install the latest firmware via Kies but have been unsuccessful. Kies either endlessly cycles from one 'Prepare for firmware upgrade' window to another, or produces an error window (Insufficient disk's [sic] free space (requires at least 3000MB)). The latter cannot be correct as I have significantly more disk space available
Also discovered another annoying bug. Any saved emails that I want to delete have to be deleted twice.
Any tips would be much appreciated as, frankly, this is beginning to do my head in!