Canon IXUS i User Manual page 12

Do not operate the flash with dirt, dust or other items stuck
to the surface of the flash.
Be careful not to cover the flash with your fingers or
clothing when shooting.
The flash may be damaged and emit smoke or noise. The
resulting heat build-up could damage the flash.
Do not touch the surface of the flash after taking several
pictures in rapid succession.
Doing so could result in burns.
10
Flash