Virus Here, Virus There… Virus, Virus Everywhere

I got a phone call this morning from a client.  Seems someone in his organization clicked on a link in an email and got immediately whacked with a virus that wiped out his Windows desktop icons and all the program entries off the Start button.  The offending email was in his personal account on one of the free webmail services (Yahoo in this case) and therefore had not been scanned by our corporate mail scanner.