So your only problem is the remastered ISO - the other two ISOs work fine?
You can test ISOBOOT from an E2B drive by holding down the SHIFT key before you press ENTER to run the ISO from the menu.
It is probably easier to start a Chat session with me on the website if the ISOBOOT web page does not help you.
If the ISO contains a casper-rw file, you will probably need to extract it to the root of the E2B USB drive.
If the initrd file cannot be found, then ISOBOOT is probably looking for the wrong file. Look at the isolinux.cfg or grub.cfg file inside your remastered ISO file to see what cheat code parameters it is using. Then make a new ISOBOOT.g4b file as described on the isoboot web page above. If the iso is using initrd.gz then you will need to add the 'try' lines into the :.isoubu code section.
Subject Re: Remastered Lubuntu doesn't boot