Michaelsuen,
Have you tried Repairing Disk and Disk Permissions?
To repair Disk and Disk permissions you have to start your Computer in Recovery Mode.
Restart your mac -> Hold down ( Command ) and ( R ) keys at startup.
Choose ( Disk Utility ) -> Select your Hard Drive ( Macintosh HD ) [*Note if you have FileVault turned on you have to enter your password to unlock it.] -> Select ( Repair Disk ) -> Wait a moment until it finishes -> Select ( Repair Disk Permissions ).
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It could be the com.apple.loginitems.plist has gone corrupt. I know that in older version of Mac OS you could remove these and a lot of the time it would fix strange issues related to them. Although I would move it to the Desktop and restart to see if it helps, if it doesn't I would put it back.
( Macintosh HD ) -> ( Users ) -> ( Your User Name ) -> ( Library [Hidden Folder] ) -> ( Preferences ) -> here you will find ( com.apple.loginituems.plist )
**Helpful Tidbit**
In Finder while holding down the ( Option key ), select the ( Go Menu) and select ( Library ) it will take you to your users hidden library folder.
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Hope that helps,
Weston
Supporting Articles
About Disk Utility's Repair Disk Permissions feature
OS X: About OS X Recovery
Resolve startup issues and perform disk maintenance with Disk Utility and fsck