Q Drive Pulse has shown a warning that one of my preference files ‘may be corrupt’, and advises that I put it in the Trash. Is that wise, and why is it corrupt?

A Several tools check through the Property List (.plist) files scattered in various Library folders to ensure that they are intact. Drive Pulse is one of those apps, and has here discovered that this file, storing preference settings, is broken. Quit Safari, locate the file in the path given, and put it in the Trash.

When you next start Safari, check through its preference settings and correct anything that has become incorrect. It will automatically write out a fresh, uncorrupted .plist file. This might save you from sporadic crashes, perhaps.

Comments Early versions of OS X stored Property Lists as plain text XML files, but many are now kept in a binary, compressed format. The unfortunate side effect is that, if one becomes damaged, the whole file is likely to become unusable.

This can account for preference settings not ‘sticking’ properly, when the damaged file cannot be overwritten, and some instability in apps which access the file. The solution is invariably to trash the file, as the next time that you use the app, it will recreate any missing settings files that it needs, although they may contain default settings rather than your personal ones.

If a Property List contained settings that would be impossible or tedious to create afresh, you could try copying an older version of the file from your Time Machine backup, but you would have to be careful that you do not replace the corrupt file with another copy that is just as corrupt. Settings can also change between app versions too, and putting a very old file back in place of the corrupt one may cause just as many problems.