Why my pc wont let me play games?

Hi there i recently bought some pc games because iv wanted to get into that for a while the first one played for a few minuites got off and then got back on but it wouldnt let me play i tried another game and it logged on created an account and everything but when it got down to the game play it shut down and i ended up back on my desk top. whats the problem? could my anti virus have something to do with this, i know its not the specs on the computer because its rather new and the games i bought are pretty old, anywho if anyone can help it would be very much so appreciated.