My computer can only play one video game after restarting. How to solve this?

So yesterday I was playing LEGO Indiana Jones 2. I quit because my favorite TV show started. After the show ended, I opened the launcher and clicked "Play". I waited for a minute and it didn't play, so I repeated the previous action. Didn't work. And I gave up after try number 30. I then tried installing Splinter Cell: Chaos Theory. It came up with a window asking me "Do you want to allow the following program with an unknown publisher to make changes to your computer?" I clicked "Yes". It didn't work still. I restarted it and started playing LEGO Indiana Jones 2 and it worked. Then the game crashed and I Alt-Tab'ed and closed the game. I ran the game again. Didn't work. So now I have to restart before I play any game. I have an ASUS K53S and additional details for my PC are: it has an Intel i5 Core, Nvidia GeForce GT 540M Cuda 2GB, it is a Windows 7 and it can run Blu-Ray. I also have Alcohol 120% for playing some ISO video games and I have a BD-ROM for these games. Last time I checked, the CD-DVD-ROM thingy turned into another BD-ROM. PLEASE HELP!