Hammer locks up after playing map

[PixelTricks]

I can play test a map fine, but after I exit the game and return to the desktop, the pc is in a lagged/locked up state. I have to end task hammer to get control of the pc back.

Really annoying.

 

[Pegg]

if you start a compile then close hammer before the compile is done the compile tool keeps running (vbsp, vvis or vrad)