What computer operating system? If Windows, what is the video card/graphics card that your computer uses?
Please look at the burn to with and with the following preference disabled in Edit Menu/Preferences/General
"Use Hardware Acceleration (works on Intel HD Graphics 2000 and higher)".
If you are using Premiere Elements 13/13.1, then you definitely do not want to be burning to Blu-ray .iso file if the file size of the .iso produced is expected to be greater than 1 GB.
See details in the following and see if they apply to you. Issue was resolved in 14, but not 13/13.1.
Please consider, and give more details.