iMac trying to connect to another iMac

Have you tried turning off File Sharing in System Preferences>Sharing?

There are many possible causes for this issue, and it may be very hard to resolve without wiping your account clean of everything except documents as a last resort. Please take each of the following steps that you haven't already tried. Back up all data before making any changes.

If you get the alert in the login screen before you log in, stop here and ask for instructions.

Step 1

If you get the alert as soon as you log in, it's probably caused by one of your login items or by software that otherwise loads at startup or login. Ask if you need help identifying it. Known offenders are "1Password" and "Adobe Resource Synchronizer."

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 Printers & Scanners pane in System Preferences and delete any network devices you no longer use.

Step 5

Triple-click anywhere in the line below on this page to select it, then copy the text to the Clipboard by pressing command-C:

~/Library/PDF Services

In the Finder, select

Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing 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 5 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

Resources such as images or sounds stored on the server may have been added to various applications. Examples would be pictures added to Contacts and custom sounds added to Mail. The range of possibilites here is practically infinite, so I can't be more specific. You might get a hint by launching the Console application and looking for error messages that appear at the same time as the alerts.

Step 9

Disconnect all wired peripherals except those needed to start up. Start up in safe mode. Test. After testing, restart as usual (not in safe mode) and verify that you still have the problem.

Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Ask for further instructions.

Step 10

Triple-click the line below 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 11

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.

Check your System/Users & Groups/Login Items preference pane:

Boot into the Recovery volume (boot with the Command + R keys held down), select Disk Utility and repair both the disk permissions and the disk. Reboot normally and try again.

Delete the shared printer in the Printers & Scanners preference pane and test.

You can add back the printer, but if the Mac it's connected to is not available on the network, you'll get the alerts. Your other question should be topic of a new thread.

Running the Mac OS X maintenance scripts on Maverics 10.9.4

An easy way is to download Onyx and run them from the Maintenance/Scripts section.