I keep getting this error after upgrading to 1.4.3 [10393]:

'The script functions-image.php has changed.'

I have reinstalled zp-core and have run setup multiple times but it doesn't solve the error.

How can i fix this?

You get this message if the file size of the script does not match what setup saw when Zenphoto was installed. As to why that would change without some outside intervention, I have no idea.

You can try installing the nightly build. At least that will be a different copy of the files.