sounds like you are not converting the ISO image to NME format compatible before you burn your games man, NME backups only work if burned a certain way, you need to do a bit more research before you burn a 15 disc pack of coasters as was the case with me.
this is what i do to make my discs boot properly on my NME 2.0 elite 79fk.
1) Extract image (I use xbox backup creator and use a SH-D162C drive w/Kreon F/Ware )
From this point on it seems like alot of people are doing different methods to prepare the ISO for the burn, i have tried exactly what others do to make theirs and i get a mixed bag effect, some will load and others will say unplayable disc even tho they were burned the exact same way. I have found a way to get 100% success with burns for "MY SETUP".
this is what i did/have done.
OK, so this is taking it from the very top, after i had made countless coasters and was pretty angry that i wasted about 40 bux worth of dvds, i was looking at the NME site and it says something about un-installing CLONE CD, then REINSTALL.
that was step 1, uninstall then reinstall clone cd did that.
dumped image then used the NME Associator to patch up the image, burned it and got a coaster.
but i have also read quite a few peoples posts that say thats all they need to do, extract image, patch with NME associator, burn, play. not working for me tho.
ok, so i was going back thru and puttin in some VERY old backups i had made before i had my kreon drive, and found that a few of them worked, and they had been prepared to SS merge program.
so my next step was to try something with that again
and this is where i found that i was able to get 100% working backups every time, not a single coaster since then,
1 extract image
2 open up Mulleter and check the image integrity, while in mulleter, extract your SS file from the image, and also make the .dvd file.
3 open SS merge and inject the ISO image file, then inject the SS file you extracted earlier thru mulleter
and hit the big button in the middle that says something like create layer break file, once its done.
4 open up NME Associator, on the default tab inject the ISO image file, AND the SS file once again, once those are loaded into the program, SWITCH to the CONVERT tab, do not hit the button on the 1st tab (default tab) just load the image stuff onto it, then switch to the CONVERT tab, once there hit the CONVERT button, it will ask a couple of questions just hit yes or ok, once its completed doing its thing, i burn, and get GREAT SUCCESS!
hope that helps you