Windows 7 - WMP doesn't fully quit after watching MKVs via Shark007

Whenever I play a .mkv, I notice that even after I quit WMP (and the window closes), I have to go to the task manager and quit wmpprocess.exe in order for it to release the file (so I can move or rename it). I've also noticed that ffx and Direct vob sub also stay open in the taskbar, and can have multiple instances going, one for each video i had recently watched. I can hover over them with the cursor to make most instances dissapear, except for once instance of each applet, which only go away onec I quit wmpprocess.exe


Question 1: what can I do so that WMP releases .mkvs after playback and fully quits?

Question 2: Is there an alternative codec pack for 64bit wmc? Just needs to support .mkv playback with subtitle support, preferably with an easy to understand interface.
I find Shark007's preferences too confusing, and when I asked on Shark007's forums for help I got an awfully laissez-faire approach to my question. That makes me a bit hesitant about support for this software.

I'm sorry that I lack the time to discuss the various quirks that come along with choosing to use A Microsoft Operating System. My forum is for the sole support of using my codec releases. Discussing issues not related to my software is not something I have the time for.

Which is why I'm asking here for what in Windows might be causing it.

That being said: I had just checked it again, and it is no longer doing it. I have to check after a restart and connecting via my Xbox to verify that it is gone. The only real thing I did was reinstall (tried CCCP and DivX Streamer, but CCCP is 32bit only and DivX streamer doesn't do subtitles), which has reset all configurations to default.