GUI crash when changing memory priority of terminated process [ACCEPTED]

[BenYeeHua]

PL GUI crashed when I changing the closed process memory priority.
For example, when I am restarting the Nightly, I open PL - Active Processes, right click on Firefox.exe, change the Memory priority-Always-None.
At that time, the Firefox.exe is closed, and PL GUI crashed as it can't change the closed process.

This is the crash dump.
https://docs.google.com/file/d/0Byrzq04hUm-oeUhiZ1BlcENIX0U/edit?usp=sharing

[Jeremy Collake]

Thanks! I will evaluate this and fix it up.