I can find nothing about an E16 error.
The Canon site says to find out the meaning of error codes, to contact Canon Tech Support:
I just bought a brand new Canon SD400 and a SanDisk Ultra II 1.0 gig Secure Digital memory card.
When I use the fast frame rate (60 frames/sec), I often get an "E16" error and then my camera switches off.
Can somebody help me out with this? I have searched all over the net for a solution to this, but there isn't much out there regarding this error.