When I start up my desktop it ends on the desktop picture and starts flashing.
Start up seems fine at first, with the start up sound, then the apple logo and then when the loading bar indicator finishes a message box shows with an exclamation mark in a yellow triangle, but is blank otherwise. THEN, the desktop picture starts to flash.
Clarification question - is the computer fully booting?
Yes, it seems to be fully booting.
Might be a corrupt .plist.
Do a backup, preferably 2 backups on 2 separate drives.
Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J. When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Select Library. Then go to Preferences/com.apple.finder.plist and com.apple.desktop.plist. Move the .plists to your desktop.
Re-launch Finder by restarting the computer and test. If it works okay, delete the plists from the desktop.
If the same, return the .plists to where you got it from, overwriting the newer one.
Thanks to leonie for some information contained in this.
desktop picture flashing at start up
