Although I have been using CHDK for some years now (Powershot A640), and have been very grateful for the marvellous extra functions, a recent problem has prompted me to join the forum.
CHDK boots automatically when I switch on the camera (SD card in locked mode) and works as you would expect; but it all goes to pot when I flip the screen through 180 degrees to make a self portrait - for passport purposes, not vanity! The display disappears but returns if the screen is moved back by 10 degrees or so; it's just about possible to set up a self portrait at this angle but very awkward if I want accurate framing. Going into Alt mode restores the display turn function fully, but of course this disables the shutter and is for running scripts. Disabling CHDK by unlocking the SD card and reinserting in the camera also restores full function to the display, so it seems the camera itself is OK.
I would be very grateful for any comment if more experienced users have an idea what might be happening. I don't mind the embarrassment if I've missed something really silly!