This command works, and behaves as expected: ultraiso -in 1.iso -optimize -compress 6 -out 2.iso
This command gives an EAccessViolation!!: ultraiso -in 1.iso -optimize -compress 6 -out 2.isz
So just changing the output extension from .iso to .isz (as it should be done to signify the image is now compressed) causes this abnormal termination. Using .isz on both input and output filenames does the same thing.
I'm running WinXP Pro 64bit SP2. This occurs on and ultraiso premium 8.6.6 and some previous versions as well, I think.
Overall, the handling of commandline args could be much improved -- I get messageless exits or crashes a lot of times when something's wrong with the arguments.