I am just trying to do an on-demand scan on my pc, but the scanner could not start....it just flashes then gone... ... The AntiVir Guard was working properly and I can always see the umbrella open, and of course doing it job securing my pc, and I can also disable it if I want to. The problem was that, I could not do to use the on demand scanner to scan my pc, everytime I try to start scanning it just flashes and disappears. What should I do, is there need to re-install the program? Or maybe, I have to download the latest version?