I was using Microsoft security essentials for a long time in my windows 7 (64 bit) PC. Once I had avast free edition but it always need update which needs a good amount of data offer that I cannot afford to get, so I left it. I cannot buy any paid version of any. Recently my USB got Trojan infection from some internet cafe and was unable to open it since it developed a new shortcut. My AV detected it but didn’t fix it and I cannot use my usb anymore even after formatting. Then I came to know that MSE is not so good and up to date. Then I tried Bit defender free edition, then vaccinated usb from some other security software. Then I could open folders in usb. After some days that vaccination of usb expired. Today my Bit defender stopped working when I tried to scan that usb, and it repeatedly asking for restart as it cannot solve some issues, although I restarted many times. Then I changed to panda free AV. It was installed correctly but when I tried to scan it showed error. I downloaded again but didn’t work. Then I came to 360 total security. Looks good till now. Don’t know what will happen this time.. Can anyone say why Bit defender and panda didn’t work for me?