Half of my shortcuts just disappeared from my desktop. Why?

I use a program System Mechanics 10, as a cleaning program , but besides that hasn't windows ever asked to remove unused desktop icons? If it is not that then a small infection or glitch, would have tried a system restore, I have proven it can remove simple malware, that may have got your icons back and removed infection if any at the same time? My security is Norton Internet Security 2011 and a purchased version of Malware Bytes, in protection mode.