It's the Steam Summer Sale and I bought a game called Reus. I downloaded it clicked play and then it asked for the administrator password, I put it in and then my Steam crashed. Why did this happen?
Given what you have said in your comments, I think the best course of action would be to ask your dad to log on to the computer under his account, log in to your Steam account, then run the games you are having the issues with crashing on. If he can get on them fine, switch back to your account and try again. My reasoning is that you not having administrative privileges is probably the culprit and him being the one to get the first runs and installs completed will solve your problem.
If this does not help, I suggest uninstalling the games which crash and then downloading/installing/running them for the first time on your father's account.