Using Blender r51828 on Windows 7, 64+ bit.

When you add a Blur node in the compositor, it crashes.

To replicate:
1. Open the default scene
2. Render it
3. Go to the compositor
4. Add a blur node and connect to the render layer. It will crash immediately.

Not sure if it's just a windows issue or across the board. Just thought I'd make it known.

Cheers.