There is a firmware update for EOS 1000D
Firmware Version 1.0.6 incorporates the following changes.

Some cameras may exhibit a phenomenon in which the LCD monitor does not display, the shutter does not release, and the busy indication remains lit in the viewfinder.
The message, "Err 99 Shooting is not possible. Turn the power switch to <OFF> and <ON> again or re-install the battery", appears on the camera's LCD monitor, and after the above operation is carried out, the LCD monitor displays in a language that is different from the actual language setting.
Firmware Version 1.0.6 is for cameras with firmware up to Version 1.0.5. If the camera's firmware is already Version 1.0.6, it is not necessary to update the firmware.

http://web.canon.jp/imaging/eosd/fir.../firmware.html