Sometimes when you are infected with a Trojan/Virus/Spyware, the malicious program may prevent your Computer from opening various Security Software Websites and Online Scanners!
Just download the Portable Scanner using some other Computer and Run the Scanner in the infected computer. See Downloading Instructions
Also, The scanner is saved under a random filename, so that malware infections won’t block the scanner.
Of Course! A very useful and handy utility.