It could be that SELinux is interrupting the file open calls by IDL/ENVI somehow in this case, If the image files you are opening are located on external hard drives or network mounted drives, try moving them to be local to the machine running IDL. Those can sometimes cause issues with file reads into IDL due to the slightest of latency, especially when opening a large number of large files.

However, since you mention that resuming the program often proceeds normally, another solution here would be to just use CATCH to prevent IDL from stopping when the file is not read properly. It is possible retrying immediately after would successfully read the image file. See this help page about how to recover from errors: https://www.l3harrisgeospatial.com/docs/controlling_and_recoveri.html