please I need help

Hello My name is Edgar and i am new to this site. I joined up because I need serious help. Im not that good with pc computers since I usually had a mac all my life. I bought a Dell inspiron 6400 a week ago. I believe i contracted a virus or spyware on my laptop. I have no idea how to get rid of it. Its the first time it ever happened to me so when it occured I was scared and nervous and did not know what to do so I just turned off the computer. This happened yesterday. When I turn on my laptop it starts up but when its finished starting up, in the welcome screen i get a message saying "The Application failed to initialize properly(0xc0000005). Click on OK to terminate the application." after that in the main screen all it shows is my background picture i put. It does not show anything else. There is no applications or start button or anything. All i see is the mouse pointer and the screen. Please help me with this I really need to get rid of the problem. Thank you very much and i will await for somebody to respond.