Thank you very much for your replies. I tried your suggestions and still nothing works. There was no .GFC file anywhere in the download from the CHDK Download page.
It's not in the download, it is created by CHDK when it runs.
I tried everything and even deleted everything on the SD card except for the DiskBoot.Bin file and still, when I turn the camera on(Via the Play Button), the Canon Splash Page shows in the LED Screen along with the word ***Autostart***.
Clearly you did not, because the CHDK CFG (called CCHDK.CFG) file is stored in the CHDK folder. If this file is not present, the default settings are used, and the default settings do not include autostarting any script.
If you are using a multi-partition card, it may not be visible. In that case the simplest solution is probably to start over, by formatting the card in the camera. As long as you unlock the card, CHDK will not boot, so you should have no trouble formatting the card.
This displays for about 12 seconds, then the camera turns itself off. Pressing the shutter button does nothing. The shutter button feels like it would if the camera was turned completely off.
The shutter button always feels the same, it's an input only. If you fully press the shutter when the a script is running, the script will be interrupted. However, if you selected a random unknown script, it could crash your camera before that happens. What you describe (the camera shutting down after a few seconds) is the camera crashing.