Problems after stopping Safari install! I can't open programs! URGENT!

I started to install the new Safari, but I realized it was going to have to restart, and I wasn't ready for that yet, so I tried to stop. I had to force quit, and maybe that was a mistake.

Now, I can't open up any install programs (e.g. the Safari installer), I can't open Software Update, I can't open Quicksilver or Speed Download or some of my other programs. They start to open, then they close. Does this have to do with Safari being gone? Because the installer deleted Safari completely. How do I fix this?

God, I hope I haven't completely screwed up my computer! This can't be happening!

Please help, if you can.