sweetmaple7 wrote:
A few days ago, Mail, Maps, "com.apple.ichat" (as a grey question mark icon), "Manager" (a circular blue App Store icon), System Preferences, and Launchpad all suddenly showed up in a row in my dock. They won't go away when I try to remove them from the dock. Any suggestions?
What else changed a few days ago...(?)
What part of the Dock—

Are you logged into the correct account
You should see your user name in the drop down >Log out and log back in.
Remove an item from the Dock: Drag the item out of the Dock until Remove is shown.
Use the Dock on Mac - Apple Support
if no resolve try a Safeboot——SafeBoot How to use safe mode on your Mac - Apple Support will sort many anomalies
Takes a bit longer to get to the login screen, does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, font cache, etc., third party system modifications and system accelerations are disabled
Login and test. try removing your items from the Dock. Reboot as normal and test. Caches get rebuilt automatically.
a reboot will put it back to normal mode.