Este é um problema conhecido: Os ícones estão corrompidos depois de acordar do modo de suspensão .
A ajuda diz:
There is a bug with some icons when resuming from suspend/hibernation but only when using nVidia proprietary drivers.
This bug has already been reported a few years ago but feel free to add new comments there: http://www.nvnews.net/vbulletin/showthread.php?p=2289131 (and/or report this bug to nVidia devs again ).
But there is a workaround: you can launch a daemon which will relaunch the dock when resuming from suspend/hibernation.
- Download this file here (click on 'download file link on the top) (source: LP: #535065)
- Launch it at startup (help here) by adding a new entry with this command: python /path/to/the/file/refresh_cd_on_resuming.py
Note: you can also use a program which does the same thing but coded in C: https://bugs.launchpad.net/cairo-dock-plug-ins/+bug/535065/comments/12 .