Macintosh error meaning Invalid Physical End Of File. A very bad thing, made more so by the fact that Disk First Aid (the scandisk of MacOS) cannot fix it. It happens when there is a problem with the length of a particular file. This condition can result from frequently shutting down improperly, crashing the computer, or using Force Quit on an application while it is still writing to the disk.

The Mac version of Norton Utilities has a fix for Invalid PEOF errors, but Diskwarrior is more highly recommended.

Apple's official solution (as per their TIL) to the problem is to reinitalize and reinstall.