Outlook data file lock & Lync

In brief: Running Lync with administrator right will lock Outlook data file (the *.ost file that sync with Exchange, not the *.pst).

In detail
On a rare occasion, I found that whenever I start up Outlook 2013, I hit the error message below and it prevent the Outlook from starting up.

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Outlook Data File
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The file C:\Users\<UserId>\AppData\Local\Microsoft\Outlook\user.name@domain.com.ost is in use and cannot be accessed. Close any application that is using this file, and then try again. You might need to restart your computer.
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OK  
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It happens after I done archiving email, closed Outlook to make a backup of the archived PST file to a backup location. Last time when I hit the error (not on the *.ost file, but on the *.pst file) it was due to the Windows Search services is locking up the *.pst file for indexing. Stopping that service will resolve it, just need to start up the service again after Outlook is started.

But this time, I tried the same method, it doesn't work. I then recalled Lync is storing message history in Outlook, so it could be the locking source. I closed Lync and start up Outlook again, the error doesn't occur, resolved.

Out of curiosity, I was wondering why would Lync lock it that way? Then another thought came through, the "Run as administrator". I run the Lync with administrator right due to I need to do a screen sharing of another program that's running under administrator right.

I done a few test, running Lync normally won't lock it, and running Lync as administrator will lock it.

So if the machine has both Outlook and Lync, make sure:

1. If Lync doesn't needs administrator right, Outlook and Lync start up sequence doesn't matter
2. If Lync needs administrator right, start up Outlook before Lync