Virus alert

was informed by one of my site members that he.. well i'll let you read his post...
Sabby,
I went to sign into the DIV 1 server and my security software immediately went nuts.
Here's the Virus: Exploit.PDF-JS.Gen
Please check into it.
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I received no pop-up warnings, nor could i initially find anything unusual. Not even an image had been added to site in over a week, that a virus can be hidden.. i checked all post and came up empty..I'm Not the "sharpest tool in the shed"when it comes to this sort of stuff.. i thought it might be something effecting forunmotion as a "whole", but my brief review of today's post show no other reports of said problem/virus.. Any advice/help?

What Security Program are they using? I ask this because there is some programs that has false warnings.