Please take each of the following steps that you haven't already tried. Back up all data before making any changes.
Step 1
If you get the warning as soon as you log in, it's probably caused by one of your login items or a system modification that loads at startup or login. Ask if you need help identifying it. A common offender is "AdobeResourceSynchronizer," which is a component of some Adobe products.
Step 2
If there's an icon representing the server in the sidebar of a Finder window, hold down the command key and drag it out.
Step 3
In the Finder, press the key combination command-K or select
Go ▹ Go to Server...
from the menu bar. In the upper right corner of the window that opens is a Recent Servers popup menu represented by a clock icon. From that menu, select
Clear Recent Servers…
and confirm. Test.
Step 4
Open the Print & Scan pane in System Preferences and delete any network devices you no longer use.
Step 5
Triple-click the line below to select it, then copy the text to the Clipboard (command-C):
~/Library/PDF Services
In the Finder, select
Go ▹ Go to Folder...
from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return. A folder may open. If it does, move the contents to the Desktop, or to a new folder on the Desktop. Log out and log back in. Test. If there's no change, put the items you moved back where they were and continue.
Step 6
Open the folder
~/Library/Preferences
as in Step 3 and move the file named "loginwindow.plist" items in that folder to the Trash, if it exists (it may not.)
Log out and back in again, and test.
Step 7
Other possible causes are references in the iPhoto, iTunes, or iMovie library pointing to the server, and bookmarks in the Preview application.
Try rebuilding the iPhoto library.
Step 8
Triple-click the line below on this page to select it:
/System/Library/CoreServices/Directory Utility.app
Rght-click or control-click the highlighted text and select
Services ▹ Open
from the contextual menu.* The application Directory Utility will open.
In the Directory Utility window, select the Directory Editor tool in the toolbar. Select Mounts from the Viewing menu in the toolbar, and /Local/Default from the node menu, if not already selected. On the right is a list of names and values. By default, the list is empty. If it's not empty, post a screenshot of the window and stop here.
*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). Open a TextEdit window and paste into it (command-V). Select the line you just pasted and continue as above.
Step 9
Open the following file as you did in the last step:
/etc/auto_master
It will open in a TextEdit window. The contents should be exactly this:
#
# Automounter master map
#
+auto_master # Use directory service
/net -hosts -nobrowse,hidefromfinder,nosuid
/home auto_home -nobrowse,hidefromfinder
/Network/Servers -fstab
/- -static
If there are any other lines in the window, post them. Otherwise, close the window.
