OK, Just installed Hammer on my friends computer and he has the exact same problem as you. Compiling problems and even the grid shown on first startup.

I have tried to figure this out, and what I have come up with, is that it has something to do with his steam account name, being is email address, contains both '@' and '.' (Dot) This seems to confuse hammer, and it puts the bsp file in his account name folder, under 'steamapps'.

Do your account name contain any special chars?