1.0.6 isn't available as a download as far as I know. Why do you need this specifically?
You could try dumping the firmware using the toolkit linked here,
http://chdk.setepontos.com/index.php/topic,2750.0.htmlI've run this on my 5D2 but I can't tell if it worked or not until I get a new CF card reader. I wanted a copy of the old firmware before I updated.
Copying the old firmware to your camera may solve the problem but would come with considerable risk.
