I loaded up the Source SDK today and ran Hammer - and my mouse is stuck in camera mode in both 2D and 3D mode. I googled - and found an existing thread on this problem - but the solutions mentioned (e.g. pressing the 'Z' button) - don't work.

So in other words:

I select the brush tool for example - but I can't click anything and it the mouse will only continue to move the camera.

Has anyone come across this?
Anyone know how to fix it?

I heard that re-installing Source SDK several times will fix it (which I'm currently trying).