Computer guru help needed!!?

Just bought a new Gateway desktop and for some reason …anytime we click on an application, no matter what it is, the computer just freezes up, requiring a hard reboot (turning off the computer at the powerstrip). It won’t let us do anything. We use the computer primarily for surfing the internet. Should I run the antivirus software and see if that cures the problem before taking the tower back to Best Buy to have them run a diagnostic or do you think that’s a bad idea? Thanks.

This happens even when IE7 is not already running. Pop-ups include "WinAnonymous", and antivirus software keep detecting a trojan called "Virtumonde", and keep successfully cleaning it out. However, the problem does not go away.

I have a Dell Inspiron 1520 laptop. My antivirus software was Symantec. Last night, i uninstall Symantec and installed Trend Micro Internet Security. The installation completed successfully. Than I tried to do the updates for Trend Micro and after about 15 minutes of updating, an error message came up saying it’s not finish updating and can’t update or something like that. Than suddenly, the screen went gray. I tried rebooting and it kept pushing me into safe mode and I had to run a repair but nothing is working. Every time I start the laptop it goes in that safe mode and wont even let me get on. I took it to Best Buy for a diagnostic (waiting for response) but wanted to know if this has this happened to anyone??????? Do you think it’s hardware or software??