No finder on login. Blue screen.

I'm working on a relatives MacBook Pro 17-inch 6,1 running 10.6.8

Regular boot has nothing except a blue screen. I can move the mouse around, but there is literally nothing else that can happen.

Tried booting into safe mode, ran ClamXav and it had 4 different results. Deleted those. I also deleted, using app zapper, something called Tuneupmymac that had been installed somehow.

Tried doing the usually single user mode stuff and that brought back the ability to use the login screen, and the blue screen is now the default mac galaxy background. Other than that, still no finder.

I'd really hate to have to erase and start their computer over again, so I'm wondering if anyone had any ideas.

Thanks!