Dual Display Problem: Primary screen swaps randomly on startup

On startup there should allways the same main monitor until the login window is shown. This physical start monitor should also the logical main monitor defined by system preferences. Switch the dvi cables, if not. Have a look at the system preferences / monitors. There you can drag the menu bar to your main monitor.

Also the preferences for dock and mission control affect the main monitor (menu bar, dock).

I'm using a iMac with two dell monitors and i have access to a mac pro with two eizo monitors. They all work fine with Mavericks.

Hope this helps you. If not, there maybe a problem with your preferences files.

The preferences files are at

~/Library/Preferences/ByHost/com.apple.preferences.displays...plist

~/Library/Preferences/ByHost/com.apple.windowserver...plist

If there are errors, they should listed at the system log. Check the Console app after a reboot.

Searching for "Display Preferences lost on reboot" at Google shows a similar issue with hdmi output for 10.9.0.

http://plugable.com/2013/10/22/multiple-monitor-issues-with-os-x-10-9-mavericks

Small mistake: com.apple.preference.displays...plist

That's only a small file with few settings.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

<dict>

<key>69671616</key>

<dict>

<key>recentModes</key>

<array>

<integer>2</integer>

</array>

</dict>

<key>722485709</key>

<dict>

<key>recentModes</key>

<array>

<integer>29</integer>

<integer>20</integer>

</array>

</dict>

</dict>

</plist>

Don't know if the missing file is a problem. Most trouble shooting hints for multiple monitors recomments to check and delete the plist files, restart the system and reenter the settings at the system preferences.

You can check for plist files at:

/Library/Preferences/com.apple.windowserver.plist

~/Library/Preferences/com.apple.systempreferences.plist

~/Library/Preferences/ByHost/com.apple.preference.displays.[MAC].plist

~/Library/Preferences/ByHost/com.apple.windowserver.[MAC].plist

Also files can be listed for the root user. You can check them with the terminal:

[su admin]

sudo ls /var/root/Library/Preferences

sudo ls /var/root/Library/Preferences/ByHost

With Mavericks Preferences are cached. Deleting the plist files will not allways take a affect.

Perhaps you wait for a better solution by another user.

I have only installed Maverick on my 15 in MacPro laptop..and am glad I did not install it on my 12 in and on my MiniMac ! I have discovered (after I first panicked that my desktop settings and files had "disappeared") that I can "log out" of the new desktop ( a lot of programs-to include Skype that I often use-refused to acknowledge my passwords and acted as if I were on a completely new computer that they did not recognize!) I had to create a "new user" (I simply reversed the order of my first and last names) and input a new password) after which I could log out of the Mavericks desktop, and log back on my usual/previous desktop. I have no idea why so many programs did not recognize my computer (my bank also "dissed" me as if I had accessed from a different machine!) so I just log out of the "new" desktop and log in as my "alter ego" in the old one. It is a roundabout solution, but it works. Meanwhile I do not intend to "upgrade" my other two Macs ! I DO NOT LIKE Mavericks! If I wanted complications and problems, and software conflicts, etc I would have used a PC/Windows machine!!