I had the same problem after updating from 10.7.4 to 10.8.2 and found a possible solution. There seem to be some incompatible settings in old configuration files for the dock.
I could solve this by deleting the configuration file for the dock. To do this open Terminal and type
Don't forget to make a backup copy of this file before! Or just rename it instead of delete it with a command like
mv ~/Library/Preferences/com.apple.dock.plist ~/Library/Preferences/backup.com.apple.dock.plist
After that you get a dock with only the Apple standard apps in it and a new com.apple.dock.plist is created. It is a good idea to make a screenshot of your existing dock before to remember which apps you have in there.
Perhaps you have to repeat this for all of your user accounts.
After that fast user switching works for me without transparent dock and any other problems.
I hope this will help you. Good luck.
This is solved definitivly for me.
thxRe: No dock/transparent dock after fast user switching
I have the same problem. Quickest fix is to execute the Terminal command "killall Dock".
So it's not a permanent fix but try this.
open AplleScript :
copy and paste :
do shell script "killall Dock"
and register as a application, without options.
And paste this new application in the "open" option in the users "system pref", with the "hide" option check.
Voilà, it's not a permanent fix. but an automatique fix... it's quite the same
same problem - mountain lion 10.8.2
sometimes i switched between my 2 user accounts, the dock is transparent.
switch back to the user bevor and another switch back and all is good.
i mean the user profile isn't correctly load.
wen the dock is transparent, e.g. it is not possible to change the desktop background.
so i think it's not a problem with the dock himself, ist a problem with the user account data.
This guide might help a little:
Yeah, it's in French.
To sum up, this issue happens when the icons of the Dock are rendered. Preferences or caches cause this problem.
So you can use Onyx (be careful), Clean tab › User, and check cleaning Dock icons.
If it's still not working, maybe this issue is due to font and not only icons.
Open Font Book app (in Applications folder). Look for Lucida Grande and remove all duplicates (File › Delete). You can even validate the remaining font (File › Validate font).
Well that's what MacG.co explains. Hope this will work!