winapi - Under which circumstances does the System process (PID 4) retain an open file handle?

Question

My application running on a Windows server makes use of a Jet/Access database. For some reasons around every two weeks that database file gets locked by the System process (PID 4, seems to be fixed)

After some googling I found some other users having their files locked by that special process, but different files (of course).

• What's the general reason for the System process to keep an open file handle?
• Is my application the cause for this locking situation?
• Are all handles implicitly opened by the System process? I could imagine that after a process has crashed, the handle may still be open and the System process somehow takes owernship of that handle.
• Can I do something in my application to prevent it from happening?

Answer 1

Files accessed through a share will be locked by the system process (PID 4).

Try opening compmgmt.msc -> System Tools -> Shared Folders -> Open Files to see if the locked file is listed there

See also the sysinternals forum for a way to replicate this.
Not all applications lock files when they are opened, Excel however does. I don't know if Access does the same...