File locked by system

Hi,

We are running a few server 2008 r2 64bit standard servers as file shares.  Recently we have been having a number of users coming to us with locked files.  When we look at the file it is not showing anyone has it open but states that the file is in use by system.  We either have to reboot the server or use process hacker or another program to kill the lock.  Anyone else run into this before.

Thanks

Mike