I can add SOME files and save but I cannot add ALL desired files. The original ISO size is 2.337 gb (52% capacity). The added files bring the total to 3.766 gb - well below the max. When I attempt to "save as" it immediately hangs. On closing it says "This program is not responding". I've tried on WinXP and Win7 computers using the latest UltraISO version. No luck.
I deleted some of the file on the original ISO and then tried adding the other files. This time it worked flawlessly. In other words, the additional files do not have an inherent problem.